SAS/C Library Reference, Vol. 1

strcmp -- Compare Two Null-Terminated Strings

SYNOPSIS

 #include <string.h>

 int strcmp(const char *str1, const char *str2);

DESCRIPTION

strcmp compares two character strings (str1 and str2) using the standard EBCDIC collating sequence. The return value has the same relationship to 0 as str1 has to str2. If two strings are equal up to the point at which one terminates (that is, contains a null character), the longer string is considered greater.

RETURN VALUE

The return value from strcmp is 0 if the two strings are equal, less than 0 if str1 compares less than str2, and greater than 0 if str1 compares greater than str2. No other assumptions should be made about the value returned by strcmp.

CAUTION

If one of the arguments of strcmp is not properly terminated, a protection or addressing exception may occur. If one of the arguments to the built-in version of strcmp is a constant, the compiler generates a CLC instruction to perform the entire comparison. If the variable argument is not null terminated, the character-by-character comparison may perform as expected, but a comparison by the CLC instruction may cause an addressing exception in rare cases.

IMPLEMENTATION

The compiler generates inline code for strcmp unless strcmp is undefined (by an #undef statement) to prevent this. The inline code may still call a library routine in special cases.

EXAMPLE

  #include <lcstring.h>
  #include <stdio.h>
  #include <stdlib.h>

  main()
  {
     char command[20];
     int n = 0;

     for(;;) {
        ++n;
        printf("Enter command # %dn", n);
        puts("Enter quit to terminate/any other command to continue.");
        gets(command);
        if (strcmp(command, "quit") == 0) break;

           /* Determine whether command is equal to quit. */
        strlwr(command);
        if (strcmp(command, "quit") == 0)
           exit(0);
        puts("Did you mean to say quit? (Case is significant.)");
     }
  }

RELATED FUNCTIONS

memcmp, strcoll, strncmp, strxfrm