C `string.h` Library: Functions for String Manipulation

The <string.h> library in C offers a comprehensive set of functions for manipulating strings and memory blocks. These functions facilitate essential tasks such as copying, concatenation, comparison, and searching, making string handling in C more efficient.

C `string.h` Library

The <string.h> header provides a variety of functions to manipulate strings and memory blocks. These functions help perform common tasks such as copying, concatenation, comparison, and searching.

Common C `string.h` Functions

Below is a list of functions provided by the string.h library:

Function	Description
`memchr()`	Returns a pointer to the first occurrence of a value in a block of memory.
`memcmp()`	Compares two blocks of memory to determine which represents a larger value.
`memcpy()`	Copies data from one block of memory to another.
`memmove()`	Copies data from one block of memory to another, accounting for memory overlap.
`memset()`	Sets all the bytes in a block of memory to a specified value.
`strcat()`	Appends one string to the end of another.
`strchr()`	Returns a pointer to the first occurrence of a character in a string.
`strcmp()`	Compares two strings by their ASCII values to determine which is greater.
`strcoll()`	Compares two strings based on locale-specific values.
`strcpy()`	Copies a string into another memory location.
`strcspn()`	Returns the length of a string up to the first occurrence of specified characters.
`strerror()`	Returns a string describing an error code.
`strlen()`	Returns the length of a string.
`strncat()`	Appends a specified number of characters from one string to another.
`strncmp()`	Compares the ASCII values of a specified number of characters in two strings.
`strncpy()`	Copies a specified number of characters from one string to another memory location.
`strpbrk()`	Returns a pointer to the first position in a string that contains specified characters.
`strrchr()`	Returns a pointer to the last occurrence of a character in a string.
`strspn()`	Returns the length of a string up to the first character that is not one of the specified characters.
`strstr()`	Returns a pointer to the first occurrence of a substring in another string.
`strtok()`	Splits a string into tokens based on specified delimiters.
`strxfrm()`	Transforms a string based on locale-specific rules.

Example: String Manipulation with `string.h`

Let’s see an example of some string.h functions in action:

Example: String Concatenation and Comparison


#include <stdio.h>
#include <string.h>

int main() {
    char str1[50] = "Hello";
    char str2[50] = "World";

    // Concatenate str2 onto str1
    strcat(str1, " ");
    strcat(str1, str2);

    // Print the concatenated string
    printf("Concatenated String: %s\n", str1);

    // Compare two strings
    int cmp = strcmp(str1, "Hello World");
    if (cmp == 0) {
        printf("Strings are equal!\n");
    } else {
        printf("Strings are not equal!\n");
    }

    return 0;
}

Output:

Output


Concatenated String: Hello World
Strings are equal!

This program concatenates two strings using strcat() and compares them using strcmp(). If the strings are equal, it prints a confirmation message.

C string.h Library: Functions for String Manipulation