C Library - strcmp() function

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The C Library strcmp() function is used to compare two strings. It checks each character in the string one by one until it finds a difference or reaches the end of the one string. Additionally, the strings comparison is based on ASCII values.

Syntax

Following is the syntax of the C library strcmp() function −

 strcmp(const char *str_1, const char *str_2) 

Parameters

This function accepts the following parameters−

• str_1 − This parameter define the first string to be compared.

• str_2 − This is the second string to compare with first/previous string.

Return Value

This function returns the integer value which is −

• Zero, if the string are equal.

• Negative, if the first string is less than second string lexicographically.

• Positive, if the first string is greater than second string lexicographically.

Example 1

In this example, we demonstrate the usage of string characters comparison using strcmp() function.

 #include <stdio.h> #include <string.h> int main() { char str1[] = "abcd", str2[] = "abcd"; int res; // Compare the strings str1 and str2 res = strcmp(str1, str2); printf("strcmp(str1, str2) = %d\n", res); return 0; } 

Output

The above code produces the following result−

 strcmp(str1, str3) = 0 

Example 2

To check whether the given strings are case-sensitive or not using strcmp() and conditional statement.

 #include <stdio.h> #include <string.h> int main() { char str1[] = "Tutorials"; char str2[] = "tutorials"; // Compare the strings int result = strcmp(str1, str2); if (result == 0) { printf("Strings are equal(case-sensitive)\n"); } else { printf("Strings are not equal(case-insensitive).\n"); } return 0; } 

Output

On execution of above code, we get the following result −

 Strings are not equal(case-insensitive). 

Example 3

Below the example create the strings of different size and check its comparison using strcmp().

 #include <stdio.h> #include <string.h> int main() { char str_1[] = "BOOK"; char str_2[] = "UNIVERSITY"; int res = strcmp(str_1, str_2); if (res == 0) { printf("The strings are equal.\n"); } else if (res < 0) { printf("Str_1 is less than str_2.\n"); } else { printf("Str_1 is greater than str_2.\n"); } return 0; } 

Output

After executing the above code, we get the following result−

 Str_1 is less than str_2. 

Example 4

Here, we use strcmp() to compare the two different string with the help of lexicographical order.

 #include <stdio.h> #include <string.h> int main { char str1[] = "text"; char str2[] = "notebook"; int result = strcmp(str1, str2); if (result < 0) { printf("'%s' comes before '%s' lexicographically.\n", str1, str2); } else if (result > 0) { printf("'%s' comes after '%s' lexicographically.\n", str1, str2); } else { printf("Strings are equal.\n"); } return 0; } 

Explanation

In this code, str1 ("text") comes before str2 ("Notebook") lexicographically. The strcmp() function returns a negative value.

The above code produces the following result −

 'text' comes after 'notebook' lexicographically.