Programming Language A

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1 Programming Language A Takako Nemoto (JAIST) 12 November Takako Nemoto (JAIST) 12 November 1 / 25

2 From Quiz 5 // A program to print the double of the input. int no printf("input an integer: "); scanf("%d", &no); printf("the double of it is %d.", 2 * no); quiz5-1.c: In function 'main': quiz5-1.c:7:5: error: expected '=', ',', ';', 'asm' or ' attribute ' before 'printf' printf("input an integer: "); ^~~~~~ quiz5-1.c:8:18: error: 'no' undeclared (first use in this function) scanf("%d", &no); ^~ quiz5-1.c:8:18: note: each undeclared identifier is reported only once for each function it appears in Takako Nemoto (JAIST) 12 November 2 / 25

3 From Quiz 5 // A program determines the input is even or not. int no; printf("input an integer: "); scanf("%d", &no); if(no % 2 = 0) printf("it is even."); else printf("it is odd."); quiz5-2.c: In function 'main': quiz5-2.c:7:11: error: lvalue required as left operand of assignment if(no % 2 = 0) ^ Takako Nemoto (JAIST) 12 November 3 / 25

4 Array: For multiple data to refer later int i; int x[5]; for (i = 0; i < 5; i++){ printf("x[%d]: ", i); scanf("%d", &x[i]); for (i = 0; i < 3; i++){ int temp = x[i]; x[i] = x[4-i]; x[4-i] = temp; x[0]: 1 x[1]: 2 x[2]: 3 x[3]: 4 x[4]: 5 Reverse them! x[0]: 5 x[1]: 4 x[2]: 3 x[3]: 2 x[4]: 1 puts("reverse them!"); for (i = 0; i < 5; i++){ printf("x[%d] = %d\n", i, x[i]); Takako Nemoto (JAIST) 12 November 4 / 25

5 Array: For multiple data to refer later int i; int x[5]; for (i = 0; i < 5; i++){ printf("x[%d]: ", i); scanf("%d", &x[i]); for (i = 0; i < 3; i++){ int temp = x[i]; x[i] = x[4-i]; x[4-i] = temp; puts("reverse them!"); for (i = 0; i < 5; i++){ printf("x[%d] = %d\n", i, x[i]); int x[5]; declares that x is an array with 5 elements of type int. By the 1st for statement, we can input and assign the value of each element of x. The 2nd for statement reverse the each element of x. x[4-i] x[i] temp Takako Nemoto (JAIST) 12 November 5 / 25

6 Object-like macro: For a versatile program #define NUMBER 5 int i; int x[number]; for (i = 0; i < NUMBER / 2 + 1; i++){ printf("x[%d]: ", i); scanf("%d", &x[i]); for (i = 0; i < NUMBER /2 + 1; i++){ int temp = x[i]; x[i] = x[number - (i + 1)]; x[number - (i + 1)] = temp; x[0]: 1 x[1]: 2 x[2]: 3 x[3]: 4 x[4]: 5 Reverse them! x[0]: 5 x[1]: 4 x[2]: 3 x[3]: 2 x[4]: 1 puts("reverse them!"); for (i = 0; i < NUMBER; i++){ printf("x[%d] = %d\n", i, x[i]); Takako Nemoto (JAIST) 12 November 6 / 25

7 Object-like macro: For a versatile program #define NUMBER 5 int i; int x[number]; for (i = 0; i < NUMBER; i++){ printf("x[%d]: ", i); scanf("%d", &x[i]); for (i = 0; i < NUMBER /2; i++){ int temp = x[i]; x[i] = x[number - (i +1)]; x[number - (i + 1)] = temp; puts("reverse them!"); for (i = 0; i < NUMBER; i++){ printf("x[%d] = %d\n", i, x[i]); #define NUMBER 5 means In the following, replace NUMBER with 5 It is easy to change the value of NUMBER in this style. This is called object-like macro. NUMBER is called macro name, which usually named with capital letters. Takako Nemoto (JAIST) 12 November 7 / 25

8 Tips: Assignment of arrays The following 3 programs give the same results: int v[5]; v[0] = 1; v[1] = 2; v[2] = 3; v[3] = 4; v[4] = 5; v[0]=1 v[1]=2 v[2]=3 v[3]=4 v[4]=5 int i; for (i = 0; i < 5; i++){ printf("v[%d]=%d\n", i, v[i]); Takako Nemoto (JAIST) 12 November 8 / 25

9 Tips: Assignment of arrays The following 3 programs give the same results: int v[5] = {1, 2, 3, 4, 5; int i; for (i = 0; i < 5; i++){ printf("v[%d]=%d\n", i, v[i]); v[0]=1 v[1]=2 v[2]=3 v[3]=4 v[4]=5 Takako Nemoto (JAIST) 12 November 9 / 25

10 Tips: Assignment of arrays The following 3 programs give the same results: int v[5]; int i; for (i = 0; i < 5; i++){ v[i] = i+1; for (i = 0; i < 5; i++){ printf("v[%d]=%d\n", i, v[i]); v[0]=1 v[1]=2 v[2]=3 v[3]=4 v[4]=5 Takako Nemoto (JAIST) 12 November 10 / 25

11 Tips: Assignment of arrays If { has less elements: int v[5] = {1; int i; for (i = 0; i < 5; i++){ printf("v[%d]=%d\n", i, v[i]); v[0]=1 v[1]=0 v[2]=0 v[3]=0 v[4]=0 Takako Nemoto (JAIST) 12 November 11 / 25

12 Tips: Copying an array Note that a = b does not work. int a[5] = {1, 2, 3, 4, 5; int b[5]; int i; for (i = 0; i < 5; i++){ b[i] = a[i]; for (i = 0; i < 5; i++){ printf("a[%d]=%d, b[%d] = %d\n", i, a[i], i, b[i]); a[0]=1, b[0]=1 a[1]=2, b[1]=2 a[2]=3, b[2]=3 a[3]=4, b[3]=4 a[4]=5, b[4]=5 Takako Nemoto (JAIST) 12 November 12 / 25

13 #define NUMBER 80 int i,j; int num; int score[number]; int dist[11] = {0; printf("input the number of the students: "); do{ scanf("%d", &num); if (num < 1 num > NUMBER){ printf("input a number between 1 and %d: ", NUMBER); while (num < 1 num > NUMBER); for (i = 0; i < num; i++){ printf("student No.%d: ", i+1); do{ scanf("%d", &score[i]); if (score[i] < < score[i]){ printf("the score should be between 0 and 100: \n"); while (score[i] < < score[i]); dist[score[i] / 10]++; puts("\n---distribution---"); printf(" 100: "); for (j = 0; j < dist[10]; j++){ putchar('*'); putchar('\n'); for (i = 9; i >= 0; i--){ printf("%3d-%3d: ", 10 * i, 10 * i + 9); for (j = 0; j < dist[i]; j++){ putchar('*'); putchar('\n'); Input the number of the students: 10 Student No.1: 20 Student No.2: 59 Student No.3: 38 Student No.4: 49 Student No.5: 39 Student No.6: 29 Student No.7: 50 Student No.8: 97 Student No.9: 69 Student No.10: Distribution : 90-99: ** 80-89: 70-79: 60-69: * 50-59: ** 40-49: * 30-39: ** 20-29: ** 10-19: 0-9: Takako Nemoto (JAIST) 12 November 13 / 25

14 #define NUMBER 80 int i,j; int num; int score[number]; int dist[11] = {0; printf("input the number of the students: "); do{ scanf("%d", &num); if (num < 1 num > NUMBER){ printf("input a number between 1 and %d: ", NUMBER); while (num < 1 num > NUMBER); for (i = 0; i < num; i++){ printf("student No.%d: ", i+1); do{ scanf("%d", &score[i]); if (score[i] < < score[i]){ printf("the score should be between 0 and 100: \n"); while (score[i] < < score[i]); dist[score[i] / 10]++; puts("\n---distribution---"); printf(" 100: "); for (j = 0; j < dist[10]; j++){ putchar('*'); putchar('\n'); for (i = 9; i >= 0; i--){ printf("%3d-%3d: ", 10 * i, 10 * i + 9); for (j = 0; j < dist[i]; j++){ putchar('*'); putchar('\n'); NUMBER is the upper bound of the number of data. If the value of score[i] is 0-9, then score[i] / 10 is 0 and so the value of dist[0] is incremented by 1. If the value of score[i] is 10-19, then score[i] / 10 is 1 and so the value of dist[1] is incremented by 1. Takako Nemoto (JAIST) 12 November 14 / 25

15 Multidimensional array int a[2][3]; int i, j; for (i = 0; i < 2; i++){ for (j = 0; j < 3; j++){ printf("input the (%d, %d) element: ", i+1, j+1); scanf("%d", &a[i][j]); for (i = 0; i < 2; i++){ for (j = 0; j < 3; j++){ printf("%d ", a[i][j]); printf("\n"); Input the (1, 1) element: 1 Input the (1, 2) element: 2 Input the (1, 3) element: 3 Input the (2, 1) element: 4 Input the (2, 2) element: 5 Input the (2, 3) element: Takako Nemoto (JAIST) 12 November 15 / 25

16 Function int max2(int a, int b){ if (a > b) return a; else return b; int n1, n2; puts("input 2 integers."); printf("integer 1: "); scanf("%d", &n1); printf("integer 2: "); scanf("%d", &n2); printf("the bigger number is %d.", max2(n1, n2)); Takako Nemoto (JAIST) 12 November 16 / 25

17 Structure of a function int max2(int a, int b){ if (a > b) return a; else return b; Function header: int max2(int a, int b) The 1st int is the return type, which is the type of return value of the function. max2 is the function name. Inside ( ) is the parameter type list. In this case, max2 has 2 arguments of type int. Function body: Inside { If a > b, then the return value is the value of a. Else, then the return value is the value of b. Takako Nemoto (JAIST) 12 November 17 / 25

18 Function call expression printf("the bigger number is %d.", max2(n1, n2)); It calls the function max2, giving the value of n1 and n2 as the arguments. Takako Nemoto (JAIST) 12 November 18 / 25

19 Example int sqr(int x){ return x * x; int diff(int a, int b){ return (a > b)? a - b : b - a; int x, y; puts("input 2 integers."); printf("integer x: "); scanf("%d", &x); printf("integer y: "); scanf("%d", &y); printf("the difference of x^2 and y^2 is %d.", diff(sqr(x), sqr(y))); Takako Nemoto (JAIST) 12 November 19 / 25

20 Example int max2(int a, int b){ if (a > b) return a; else return b; int n1, n2, n3, n4; puts("input 2 integers. "); printf("integer 1: "); scanf("%d", &n1); printf("integer 2: "); scanf("%d", &n2); printf("integer 3: "); scanf("%d", &n3); printf("integer 4: "); scanf("%d", &n4); printf("the bigger number is %d.", max2(max2(n1, n2), max2(n3,n4))); Takako Nemoto (JAIST) 12 November 20 / 25

21 Example void put_star(int n){ while (n-- > 0) putchar('*'); int i, len; puts("let's draw an isosceles triangle."); printf("length of the shorter edge?: "); scanf("%d", &len); for (i = 1; i<= len; i++){ put_star(i); putchar('\n'); Takako Nemoto (JAIST) 12 November 21 / 25

22 Example int scan_pint(void){ int temp; do{ printf("input a positive integer: "); scanf("%d", &temp); if (temp < 0) puts("do not input any non-positive integer."); while(temp < 0); return temp; int rev_int(int num){ int temp = 0; while (num > 0){ temp = temp * 10 + num % 10; num /= 10; return temp; int nx = scan_pint(); printf("the inversed value is %d.\n", rev_int(nx)); Takako Nemoto (JAIST) 12 November 22 / 25

23 Today s homework 1 Write a program in C s.t., for input data (max 50), it draw a histogram as follows: Input the number of the data: 7 Input data No.1: 5 Input data No.2: 3 Input data No.3: 5 Input data No.4: 4 Input data No.5: 6 Input data No.6: 2 Input data No.7: 7 1 ***** 2 *** 3 ***** 4 **** 5 ****** 6 ** 7 ******* Takako Nemoto (JAIST) 12 November 23 / 25

24 Today s homework 2 (optional) Modify the program in 1 to draw a vertical diagram: Input the number of data: 7 Input data No.1: 3 Input data No.2: 5 Input data No.3: 3 Input data No.4: 6 Input data No.5: 4 Input data No.6: 6 Input data No.7: 3 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Takako Nemoto (JAIST) 12 November 24 / 25

25 Today s homework 3 Write a program to calculate, for inputs of a 4 3 matrix and a 3 4 matrix, the product of them. As usual, send the programs as attached files to me via , with the title Homework Lecture6 by the next lecture. Please make sure to include your name and student ID number. Takako Nemoto (JAIST) 12 November 25 / 25

Programming Language A

Programming Language A Takako Nemoto (JAIST) 22 October Takako Nemoto (JAIST) 22 October 1 / 28 From Homework 2 Homework 2 1 Write a program calculate something with at least two integer-valued inputs,