strcmp() Function in C: Comparing Strings

strcmp() function in C compares two given strings and returns zero if they are same.

Syntax

int strcmp(const char *strng1, const char *strng2);

The strcmp( ) function lexicographically compares two strings and returns an integer based on the outcome as shown here:

Parameters

strng1 -first string
strng2 -Second string

Returns

Return Value	Description
Less than zero	strng1 is less than strng2
Zero	strng1 is equal to strng2
Greater than zero	strng1 is greater than strng2

Program 1

#include 
#include 
int main( )
{
   char str1[ ] = "atnyla" ;
   char str2[ ] = "atNyla" ;
   int i, j, k, l;
   i = strcmp ( str1, "feel" ) ;
   j = strcmp ( str1, str2 ) ;
   k = strcmp ( str1, "f" ) ;
   l = strcmp ( str1, str1 ) ;
   printf ( "\n%d %d %d %d\n", i, j, k,l ) ;
   return 0;
}

Output

-1 1 -1 0
Press any key to continue . . .

Program 2

You can use the following function as a password-verification routine. It returns zero on failure and 1 on success. Here your predefined password is "pass"

#include 
#include 
int main( )
{
 int a;
 a = password();
 if(a==1)
 {
 printf("password matched\n");
 }
}

int password(void)
{
	char s[80];
	printf("Enter password: ");
	gets(s);
	if(strcmp(s, "pass")) {
	printf("Invalid Password\n");
	
	return 0;
	}
return 1;
}

Output

Output 1
Enter password: pass
password matched
Press any key to continue . . .

Output 2 
Enter password: passwo
Invalid Password
Press any key to continue . . .

Point to be noted

strcmp() function is case sensitive. i.e, "A" and "a" are treated as different characters.