String Functions in C

C programming language provides several built-in functions in the standard library to manipulate strings. Here are some of the most commonly used string functions in C:

1. strlen(): This function returns the length of a string (not including the null character ‘\0’).

#include 
#include 

int main() {
    char str[] = "Hello, world!";
    int len = strlen(str);

    printf("The length of the string is %d\n", len);

    return 0;
}

2. strcpy(): This function copies the contents of one string to another string.

#include 
#include 

int main() {
    char str1[] = "Hello";
    char str2[10];

    strcpy(str2, str1);

    printf("str1: %s\n", str1);
    printf("str2: %s\n", str2);

    return 0;
}

3. strcat(): This function concatenates two strings together.

#include 
#include 

int main() {
    char str1[] = "Hello";
    char str2[] = ", world!";

    strcat(str1, str2);

    printf("%s\n", str1);

    return 0;
}

4. strcmp(): This function compares two strings and returns an integer value that indicates their relative order.

#include 
#include 

int main() {
    char str1[] = "apple";
    char str2[] = "banana";

    int result = strcmp(str1, str2);

    if (result < 0) {
        printf("%s comes before %s\n", str1, str2);
    } else if (result > 0) {
        printf("%s comes after %s\n", str1, str2);
    } else {
        printf("%s is the same as %s\n", str1, str2);
    }

    return 0;
}

These are just a few examples of the many string functions available in C programming language. It is important to use these functions carefully to avoid buffer overflows and other errors when manipulating strings.