C String Functions

C string functions are a set of functions that are used to manipulate character arrays or strings in C programming. These functions allow you to perform operations such as copying, concatenating, comparing, and searching for strings.

Syntax

The syntax for the most commonly used C string functions are as follows:

• strcpy(destination, source); - Copies the contents of one string to another.
• strcat(destination, source); - Concatenates two strings together.
• strlen(string); - Returns the length of a string.
• strcmp(string1, string2); - Compares two strings to see if they are the same.

Example

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

int main() {
    char string1[20] = "Hello";
    char string2[20] = "World!";
    char result[40];

    /* Copying strings */
    strcpy(result, string1);
    printf("Resulting string: %s\n", result);

    /* Concatenating strings */
    strcat(result, string2);
    printf("Resulting string: %s\n", result);

    /* Computing string length */
    printf("Length of string: %d\n", strlen(result));

    /* Comparing strings */
    if (strcmp(string1, string2) == 0) {
        printf("Strings are equal.\n");
    } else {
        printf("Strings are not equal.\n");
    }

    return 0;
}

Output

Resulting string: Hello
Resulting string: HelloWorld!
Length of string: 12
Strings are not equal.

Explanation

In the example above, we used the strcpy() function to copy the contents of string1 to result, and printed the resulting string. We then used the strcat() function to concatenate string2 to result, printing the final resulting string.

Next, we used the strlen() function to compute the length of result, and printed this value. Finally, we used the strcmp() function to compare string1 and string2, and printed whether or not they were equal.

Use

C string functions are commonly used in C programming to manipulate character arrays or strings. Some common use cases include formatting strings, filtering input, and parsing messages.

Important Points

• C strings are character arrays that are terminated by a null character (\0).
• C string functions may overwrite memory if the size constraints of the destination string are not respected.
• C string functions are influenced by system locale and might behave differently on different platforms.

Summary

C string functions are fundamental to manipulating strings in C programming. They allow developers to perform operations such as copying, concatenating, comparing, and searching strings. Understanding the syntax and application of these functions is essential to effective C programming.