Scheme of valuations-test 3 PART 1

Transcription

1 Scheme of valuations-test 3 PART 1 1 a What is string? Explain with example how to pass string to a function. Ans A string constant is a one-dimensional array of characters terminated by a null ( \0 ) for example: char name[ ] = H, E, L, L, O, \0 ; or char name[ ] = HELLO ; \0 is called as null character. ASCII value of \0 is 0. String can be passed into function by two ways B Ans (a) Call by value (b) Call by reference Example: #include <stdio.h> void strrcpy(char target[],char source[]); int main() char t1[0],s1[0]; puts("enter the string"); gets(s1); strrcpy(t1,s1); printf("source=%s\n",s1); printf("target=%s\n",t1); return 0; void strrcpy(char target[],char source[]) int i=0; while(source[i]!='\0') target[i]=source[i]; i++; target[i]='\0'; Write a program to input a string and calculate and print the length of the string without using strlen(). #include<stdio.h> void main(void) 1 1

2 A Ans char str1[5]; int len=0; printf("enter string whose length is to be found:"); gets(str1); while(str1[len]!='\0') len++; //here the length of string is calculated. printf("length of the string is %d", len); Write a program to search a name in a list of names using binary search technique. #include<stdio.h> #include<stdlib.h> #include<string.h> void main() int i,n,low,high,mid; char a[50][50],key[0]; printf("\n Enter the number of names: "); scanf("%d",&n); printf("\nenter the names in ascending order\n"); for(i=0;i<n;i++) scanf("%s",&a[i]); printf("\nenter the name to be searched\n"); scanf("%s",&key); low=0; high=n-1; while(low<=high) mid=(low+high)/; if(strcmp(key,a[mid])==0) printf("key found at position %d\n",mid+1); exit(0); else if(strcmp(key,a[mid])>0) low=mid+1; else

3 high=mid-1; printf("\nname not found\n"); b Explain strcpy(), strcat(), strlen(), strncpy(), strcmp() with examples. Ans Strcpy(): Syntax of strcpy: strcpy(target,source); Copies the contents of the from string including the null character, to the string Ex: char s1[1],s[9]= Good Day ; strcpy(s1,s); strcat(): This function concatenates the source string at the end of the target string. For example, Good and Morning on concatenation would result into a string Good Morning. void main() char source[]="morning"; char target[0]="good "; strcat(target,source); puts(target); Strlen() : String length: strlen() int strlen(const char* string); Strncpy(): returns the length of the string, i.e., the no. of chars in the string excluding the null char Returns zero if the string is empty char* strncpy(target, source, int size); Size specifies the maximum number of chars that can be moved at a time If the size of the from string is equal to or greater than size, then size chars

4 are moved If the from string is smaller than size, the entire string is copied and then null chars are inserted into the destination string until exactly size chars have been copied Strcmp(): This is a function which compares two strings to find out whether they are same or different. The two strings are compared character by character until there is a mismatch or end of one of the strings is reached, whichever occurs first. If the two strings are identical, strcmp( ) returns a value zero. If they re not, it returns the numeric difference between the 0. ASCII values of the first non-matching pair of characters. PART 3 a What is Structure? How structure is different from an array? Explain declaration of a structure with an example. Ans Structure is a collection of elements of different data type. The syntax is shown below: struct structure_name data_type member1; data_type member; data_type member3; ; The variables that are used to store the data are called members of the structure. We can create the structure for a person as shown below: struct person char name[50]; int cit_no; float salary; ; This declaration above creates the derived data type struct person. Array is the collection items of similar datatype. Structure Variable Declaration A structure can be declared using methods: 1) Tagged Structure When a structure is defined, it creates a user-defined type but, no storage is allocated. For the above structure of person, variable can be declared as: struct person 1

5 b char name[50]; int cit_no; float salary; ; Inside main function: struct person p1, p; Here the above statement declares that the variables p1 and p are variables of type struct person. Once the structure variable is declared, the compiler allocates memory for the structure variables. The size of the memory allocated is the sum of size of individual members. ) Type Defined Structure Another way of creating sturcture variable using the keyword typedef is: typedef struct person char name[50]; int cit_no; float salary; EMP; Inside main function: EMP p1,p ; Here the above statement declares that the variables p1 and p are variables of type EMP(which is of type as struct person).. Structure Variable Initialization For ex: struct person char name[50]; int cit_no; float salary; ; struct person p1="ram",, 3000; Accessing Members of a Structure Member operator(.) can be used for accessing members of a structure. Any member of a structure can be accessed as: structure_variable_name.member_name By specifying p1.name, we can access the name ram. By specifying p1.salary, we can access the value The various values can be accessed and printed as shown below: printf("%s", p1.name); printf("%f", p1.salary); We can read the members of a structure as shown below: gets(p1.name); or scanf("%s", p1.name); scanf("%f",&p1.salary);. Explain how the structure variable passed as a parameter to a function. And also, write a program to add two complex numbers by passing structure to a function.

6 Passing Structure by Value A structure-variable can be passed to the function as an argument as normal variable. If structure is passed by value, change made in structure-variable in functiondefinition does not reflect in original structure variable in calling-function. #include <stdio.h> struct comp int real; float img; ; Struct comp Add(struct comp c1,struct comp c, struct comp c3) // Adding complex numbers c1 and d and storing it in c3 c3.real=c1.real+c.real; c3.img=c1.img+c.img; return(c3); void main() struct comp c1, c, c3; printf("first complex number \n"); printf("enter real part: "); scanf("%d",&c1.real); printf("enter imaginary part: "); scanf("%f",&c1.img); printf("second complex number \n"); printf("enter real part: "); scanf("%d",&c.real); printf("enter imaginary part: "); scanf("%f",&c.img); c3=add(c1, c); //passing structure variables c1 and c by value whereas passing // structure variable c3 by reference printf("sum of complex numbers = %d + i %d",c3.real, c3.img); Write a C program to maintain a record of "n" student details using an array of structures with four fields (Roll number, Name, marks, and Grade). Each field is of an appropriate data type. Print the marks of the student given name as input. 8 Ans #include <stdio.h> #include <stdlib.h> struct Student

7 int Marks,RollNo; char Name[30],Grade; ; void main() struct Student s[0]; int i, Num, Found = 0; char StudName[30]; printf("\nenter the number of students\n"); scanf("%d", &Num); printf("\nenter Student Details\n"); for(i=0;i<num;i++) printf("\nstudent %d\n\nrollno : ", i+1); scanf("%d", &s[i].rollno); printf("\nname : "); scanf("%s",&s[i].name); printf("\nmarks : "); scanf("%d",&s[i].marks); printf("\ngrade : "); scanf("%s",&s[i].grade); printf("\n\n\n"); printf("\nenter the name to display marks\n"); scanf("%s",&studname); for(i=0;i<num;i++) if(strcmp(studname,s[i].name)==0) Found = 1; printf("\nmarks obtained by %s is %d\n", s[i].name, s[i].marks); exit(0); if(found == 0) printf("\nno student by name %s found\n", StudName); PART 3

8 5 a What is FILE? Explain the various MODES in which a file can be created and open successfully. A computer file is used to store data in digital format like plain text, image data or any other content. Computer files can be considered as the digital counterpart of paper documents, which traditionally are kept in office. While doing programming, you keep your source code in text files with different extensions. For example, C programming files have.c extension, Java programming files have.java extension. File Operations 1) Creating a new file ) Opening an existing file 3) Reading from and writing information to a file ) Closing a file DEFINING, OPENING AND CLOSING OF FILES Defining a File While working with file, you need to declare a pointer of type FILE. This declaration is needed for communication between file and program. FILE *ptr; Opening a File fopen( ) function can be used to create a new file or to open an existing file This function will initialize an object of the type FILE, which contains all the information necessary to control the stream. The syntax is shown below: FILE *fopen( const char *filename, const char *access_mode ); where filename is string literal, which you will use to name your file. access_mode can have one of the following values: Mode Description r Opens an existing text file for reading purpose w Opens a text file for writing, if it does not exist then a new file is created a Opens a text file for writing in appending mode r+ Opens a text file for reading and writing both Closing a File The file should be closed after reading/writing of a file. fclose( ) function can be used to close a file. The syntax is shown below: int fclose(file *fp); The fclose( ) function returns zero on success or returns EOF(special character) if there is an error b Write a program to read and display a text from the file. void main()

9 FILE *fp; char buff[55]; fp = fopen("student.txt", "r"); if(fp==null) printf( error ); while(!feof(fp)) fscanf(fp, "%s", buff); printf("1 : %s \n", buff ); fclose(fp); P.T.O.

10 6 Given two text documentary files Ramayan.in and Mahabharat.in. Write a C program to create a new file Karnataka.in that appends the contents of the file Ramayan.in to the file Mahabharat.in. Also, calculate the number of words and new lines in the output file. #include <stdio.h> #include <stdlib.h> 8 int main() FILE *fp1,*fp,*fp3; char x[0],y[0],ch; int words=0,lines=0; fp1=fopen("ra.txt","r"); if(fp1==null) printf("error in file1"); fp=fopen("ma.txt","r"); if(fp==null) printf("error in file"); fp3=fopen("ka.txt","w"); if(fp3==null) printf("error in file3"); while(fscanf(fp,"%s",x)!=eof) fprintf(fp3,"%s\n",x); fclose(fp); while(fscanf(fp1,"%s",y)!=eof) fprintf(fp3,"%s\n",y); fclose(fp3); fclose(fp1); fp3=fopen("ka.txt","r"); if(fp3==null) printf("error in file3"); while ((ch=getc(fp3))!= EOF) // Increment word count if new line or space character if (ch == ' ' ch == '\n') ++words; return 0; // Increment line count if new line character if (ch == '\n') lines++; printf("\nwords and lines in a file are=%d,%d",words,lines);

11 PART 7 a What is pointer? Write a C program using pointers to compute the sum, mean and standard deviation of all elements stored in an array of n real numbers. A pointer is a variable which holds address of another variable or a memorylocation. For ex: c=300; pc=&c; Here pc is a pointer; it can hold the address of variable c & is called reference operator #include<stdio.h> #include<math.h> main() int n,i; float a[0],sum=0,mean,sumd=0, variance, stddev; printf("enter the No of elements \n"); scanf("%d",&n); float *p; p=&a[0]; for(i=0;i<n;i++) scanf("%f",(a+i)); for(i=0;i<n;i++) sum= sum + *(a+i); mean=sum/n; for(i=0; i<n;i++) sumd=sumd+pow((*p - mean),); p++; variance=sumd/n;

12 stddev= sqrt(variance); printf("\nsum: %f",sum); printf("\nmean: %f",mean); printf("\n Standard Deviation: %f",stddev); b Explain dangling pointer and array of pointers with example? A dangling pointer is one that has a value (not NULL) which refers to some memory which is not valid for the type of object you expect. For example if you set a pointer to an object then overwrote that memory with something else unrelated or freed the memory if it was dynamically allocated. Consider an array: int arr[]; The name of the array always points to the first element of an array. Here, address of first element of an array is &arr[0]. Also, arr represents the address of the pointer where it is pointing. Hence, &arr[0] is equivalent to arr. Also, value inside the address &arr[0] and address arr are equal. Value in address &arr[0] is arr[0] and value in address arr is *arr. Hence, arr[0] is equivalent to *arr. Similarly, &a[1] is equivalent to (a+1) AND, a[1] is equivalent to *(a+1). &a[] is equivalent to (a+) AND, a[] is equivalent to *(a+). &a[3] is equivalent to (a+1) AND, a[3] is equivalent to *(a+3). &a[i] is equivalent to (a+i) AND, a[i] is equivalent to *(a+i). You can declare an array and can use pointer to alter the data of an array. Example: Program to access elements of an array using pointer. #include<stdio.h> void main() int data[5], i; printf("enter elements: "); for(i=0;i<5;++i) scanf("%d", data+i); printf("you entered: "); for(i=0;i<5;++i) printf("%d ",*(data+i) ); Output: Enter elements: You entered: What do you mean by Dynamic memory allocation? Explain malloc (), calloc(), realloc() and free()? Dynamic memory allocation is the process of allocating memory-space during execution-time 8

13 i.e. run time. If there is an unpredictable storage requirement, then the dynamic allocation technique is used. This allocation technique uses predefined functions to allocate and release memory for data during execution-time. There are library functions for dynamic memory allocation: 1) malloc() ) calloc() 3) free() ) realloc() These library functions are defined under "stdlib.h" malloc() The name malloc stands for "memory allocation". This function is used to allocate the requirement memory-space during execution-time. The syntax is shown below: data_type *p; p=(data_type*)malloc(size); here p is pointer variable data_type can be int, float or char size is number of bytes to be allocated If memory is successfully allocated, then address of the first byte of allocated space is returned. If memory allocation fails, then NULL is returned. For ex: ptr=(int*)malloc(100*sizeof(int)); The above statement will allocate 00 bytes assuming sizeof(int)= bytes. Calloc The name calloc stands for "contiguous allocation". This function is used to allocate the required memory-size during execution-time and at the same time, automatically initialize memory with 0's. The syntax is shown below: data_type *p; p=(data_type*)calloc(n,size); If memory is successfully allocated, then address of the first byte of allocated space is returned. If memory allocation fails, then NULL is returned. The allocated memory is initialized automatically to 0's. For ex: ptr=(int*)calloc(5,sizeof(int)); The above statement allocates contiguous space in memory for an array of 5 elements each of size of int, i.e., bytes. free Dynamically allocated memory with either calloc() or malloc() does not get return on its own. The programmer must use free() explicitly to release space. The syntax is shown below: free(ptr); This statement causes the space in memory pointed by ptr to be deallocated. realloc() If the previously allocated memory is insufficient or more than sufficient. Then, you can change memory-size previously allocated using realloc(). 1.5*

14 The syntax is shown below: ptr=(data_type*)realloc(ptr,newsize); PART 5 9 a What do you mean by data structure? Explain primitive and non-primitive data types. A data structure is a specialized format for organizing and storing data. General data structure types include the array, the file, the record, the table, the tree, and so on. Any data structure is designed to organize data to suit a specific purpose so that it can be accessed and worked with in appropriate ways. PRIMITIVE AND NON-PRIMITIVE DATA TYPES Data type specifies the type of data stored in a variable. The data type can be classified into two types: 1) Primitive data type and )Non-Primitive data type Primitive Data Type The primitive data types are the basic data types that are available in most of the programming languages. The primitive data types are used to represent single values. Integer: This is used to represent a number without decimal point. Eg: 1, 90 Float: This is used to represent a number with decimal point. Eg: 5.1, 67.3 Character: This is used to represent single character Eg: C, a String: This is used to represent group of characters. Eg: "M.S.P.V.L Polytechnic College" Boolean: This is used represent logical values either true or false. Non Primitive Data Type The data types that are derived from primary data types are known as non-primitive data types. These datatypes are used to store group of values. The non-primitive data types are Arrays Structure Stacks Linked list Queue Binary tree 1* b Define Stack and Linked List with example and mention the applications. A stack is a special type of data structure where elements are inserted from one end and elements are deleted from the same end. Using this approach, the Last element Inserted is the First element to be deleted Out, and hence, stack is also called LIFO data structure. The various operations performed on stack: Insert: An element is inserted from top end. Insertion operation is called push operation. Delete: An element is deleted from top end. Deletion operation is called pop operation.

15 Overflow: Check whether the stack is full or not. Underflow: Check whether the stack is empty or not. APPLICATIONS OF STACK 1) Conversion of expressions: The compiler converts the infix expressions into postfix expressions using stack. ) Evaluation of expression: An arithmetic expression represented in the form of either postfix or prefix can be easily evaluated using stack. 3) Recursion: A function which calls itself is called recursive function. ) Other applications: To find whether the string is a palindrome, to check whether a given expression is valid or not. Linked List A linked list is a data structure which is collection of zero or more nodes where each node has some information. Normally, node consists of fields 1) info field which is used to store the data or information to be manipulated ) link field which contains address of the next node. Different types of linked list are SLL & DLL Various operations of linked lists 1) Inserting a node into the list ) Deleting a node from the list 3) Search in a list ) Display the contents of list Application Sparse Matrices 10 Define Queue explain its operation with example. What are its applications? 8 #include <stdio.h> #define MAX 50 int queue_array[max], rear = - 1, front = - 1; insert() int add_item; if (rear == MAX - 1) printf("queue Overflow "); else if (front == - 1) //If queue is initially empty front = 0; printf("insert the element in queue : "); scanf("%d", &add_item); rear=rear+1; queue_array[rear]=add_item; //End of insert() delete() if (front == - 1 front > rear) printf("queue Underflow \n"); return ; else

16 printf("element deleted from queue is : %d\n", queue_array[front]); front = front + 1; //End of delete() display() int i; if (front == - 1) printf("queue is empty \n"); else printf("queue is : \n"); for (i = front; i <= rear; i++) printf("%d ", queue_array[i]); printf("\n"); main() int choice; while (1) printf("1.insert element to queue \n"); printf(".delete element from queue \n"); printf("3.display all elements of queue \n"); printf(".quit \n"); printf("enter your choice : "); scanf("%d", &choice); switch (choice) case 1: insert(); break; case : delete(); break; case 3: display(); break; case : exit(1); default: printf("wrong choice \n"); //End of switch //End of while //End of main