APPENDIX TRANSLATING BETWEEN C, FORTRAN, AND PASCAL LANGUAGES

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1 APPENDIX TRANSLATING BETWEEN C, FORTRAN, AND PASCAL LANGUAGES Here, in tabular and example form, is an outline of the main differences between C, Fortran, and Pascal. It is intended to help you overcome the barrier to translating between these three languages, rather than to substitute for learning thoroughly the language of your choice. In particular (as discussed in Section 1.2), the sample programs in this book use only the parts of C relating to numerical applications, which is a limited subset of the full language. If you wish to become a competent programmer in the C language, the References on Learning and Using C at the end of Chapter 1 should be helpful. The book by Gehani and that by Müldnes and Steele, are suitable if you are experienced in other computer languages. Kerrigan s book is specifically aimed to help the transition from Fortran to C, while the book by Shammas introduces C to Pascal programmers. The material following summarizes the aspects of C language that are used in this book, together with workable counterparts in Fortran and C. The C examples of code segments are drawn from the sample programs, and I indicate in which program a similar code segment can be found. The Fortran and Pascal code segments are likely to be correct, but they have not been tested by compiling them within complete programs. I have not attempted to indicate correspondences between the three languages for topics that are highly dependent on the computing environment, such as file declarations. In the following table the items in italics are generic names that are substituted by actual names, as shown in the examples. 423

2 424 APPENDIX Overall Structure and Procedure Declarations main() Program name function() function() void function() subroutine name() Example; See Program 2.1 program name;. function();. procedure(); main program Data Type Declarations double name ; real name int name ; integer name double array [SIZE]; real array (SIZE) int array [SIZE]; int array (SIZE) char name; character name var name : real; var name : integer; var array [l.. SIZE ] of real; var array [l.. SIZE ] of integer; var name : char; Example; Program 3.1 double rmin,dr; real rmin,dr int nterms,kmax; integer nterms,kmax var rmin,dr: real; var nterms,kmax: integer; Input and Output Console: scanf (input list ); read(*, format ) input list printf( format, write(*, format ) output list); output list read( input list ); write (output list); printf("input x1 "); write(*,* )'Input x1' write('input x1'); scanf("%lf",x1); read(*,*) x1 read(x1);

3 APPENDIX 425 Files: FILE *file name ; FILE *fopen(); fscanf (fin, format, input list ); fprintf (fout,format, output list); Example; Program 7.1 FILE *fin,fout; FILE *fopen(); fprintf(fout,"%lf", Din); read(unit, format ) get (pointer to input list file item ); write(unit, format ) put (pointer to output list file item ); (Require system-dependent file allocation) write(10,f10.2) Din put(din); Control Structures while while (condition) {action } while (xl!= 0 ) { printf ("Input xl:"); if if (condition) {action } if ( xl == 0 ) { printf ("End"); if (condition ) then action while (condition )do action while (xl <> 0 ) do writeln('input xl'); if (condition ) then action if ( x1.eq.0 ) then if(xl=0) write (*,*) 'End' writeln ("End");

4 426 APPENDIX if else if (condition) {action 1} else {action 2} if (condition) then if (condition) then action 1 else action 1; action 2 else action 2; if ( den == 0 ) if ( den.eq.0) then { x1d2 = 0; x1d2 = 0; } else else x1d2 = { x1d2 = (x1*x2+y1*y2)/den (x1*x2+y1*y2)/den; if(den=o) x1d2 := 0; else x1d2 := (x1*x2+y1*y2)/den; for for (loop condition) (sometimes Do loop) { action} for loopcondition do action Example: Program 3.1 for(k=l;k<=kmax;k++) do 2 k=l,krmax,l { term = r*term term = r*term; sum= sum+term sun= sum+term; 2 continue } for k:=l to kmax do term := r*term; sum := sum+term;

5 APPENDIX 427 switch switch (expression) { case constant 1: {action1}; break; case constant 2: (action2); break; D default: {action}; goto(st 1,st 2,.), expression st 1 action1 st 2 action2 st 1 & st 2 are statement numbers case condition of 1: action 1; 2: action 2; Example: Program 3.4 switch (choice) { case 1: series=psexp; break; case 2: series=pscos; break; } goto (1,2),choice series=psexp series=pscos case choice of 1: series :=PSexp; 2: series :=PScos; Program Operators Arithmetic Power pow (x,y) **y (Requires function) Assignment variable 1 =expression ; variable 1 =expression variable 1: =expression ; Increment & Decrement ++ increment by 1 -- decrement by 1

6 428 APPENDIX Arithmetic Compare Equal to; == Not equal to;!= Less than; < Less than or equal; <= Greater than; > Greater than or equal; >=.EQ..NE..LT..LE..GT..GE. = <> < <= > >= Logical Operators And; && Or; Not;!.AND..OR..NOT. AND OR NOT

Computers in Engineering. Moving From Fortran to C Michael A. Hawker

Computers in Engineering. Moving From Fortran to C Michael A. Hawker Computers in Engineering COMP 208 Moving From Fortran to C Michael A. Hawker Remember our first Fortran program? PROGRAM hello IMPLICIT NONE!This is my first program WRITE (*,*) "Hello, World!" END PROGRAM