C String Functions: Mastering String Manipulation

C programming offers a variety of string functions that facilitate performing different operations on strings. By including the <string.h> header file in your program, you gain access to these essential functions, enabling you to manipulate and manage strings effectively in your applications.

C String Functions

String Functions

C provides several useful string functions that allow you to perform various operations on strings. To use these functions, you need to include the <string.h> header file at the beginning of your program:

#include <string.h>

String Length

To get the length of a string, you can use the strlen() function. For example:

char alphabet[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
printf("%d", strlen(alphabet));

Output

26

Note that sizeof and strlen behave differently. While strlen counts the number of characters in the string (excluding the null terminator \0), sizeof includes the null terminator in its count:

char alphabet[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
printf("%d", strlen(alphabet));   // 26
printf("%d", sizeof(alphabet));   // 27

Output

26
27

Also, note that sizeof always returns the memory size (in bytes) rather than the actual string length:

char alphabet[50] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
printf("%d", strlen(alphabet));   // 26
printf("%d", sizeof(alphabet));   // 50

Output

26
50

Concatenate Strings

To concatenate (combine) two strings, you can use the strcat() function:

char str1[20] = "Hello ";
char str2[] = "World!";

// Concatenate str2 to str1 (result is stored in str1)
strcat(str1, str2);

// Print str1
printf("%s", str1);

Output

Hello World!

Make sure that the size of str1 is large enough to store the combined result of the two strings.

Copy Strings

To copy the value of one string to another, you can use the strcpy() function:

char str1[20] = "Hello World!";
char str2[20];

// Copy str1 to str2
strcpy(str2, str1);

// Print str2
printf("%s", str2);

Output

Hello World!

Ensure that the size of str2 is sufficient to hold the copied string.

Compare Strings

To compare two strings, you can use the strcmp() function. It returns 0 if the strings are equal; otherwise, it returns a non-zero value:

char str1[] = "Hello";
char str2[] = "Hello";
char str3[] = "Hi";

// Compare str1 and str2, and print the result
printf("%d\n", strcmp(str1, str2));  // Returns 0 (the strings are equal)

// Compare str1 and str3, and print the result
printf("%d\n", strcmp(str1, str3));  // Returns a non-zero value (the strings are not equal)

Output

0
-1