String Handling in C Programming – Complete Guide to strlen, strcpy, strcmp and More

Strings are one of the most important topics in C programming. Almost every real-world program uses strings in some form.

In this article, you will learn string handling in C programming step by step, including the most commonly used string functions with simple explanations.

What Is a String in C?

A string in C is an array of characters terminated by a null character \0.

Example:

char name[] = "Coding";

Why String Handling Is Important?

• Used in user input and output
• Required for file handling
• Important for interview questions

String Header File

All string functions are defined in the string.h header file.

#include <string.h>

strlen() Function

The strlen() function returns the length of a string excluding the null character.

char str[] = "Hello";
printf("%d", strlen(str));

strcpy() Function

The strcpy() function copies one string into another.

char src[] = "C Programming";
char dest[20];
strcpy(dest, src);

strcmp() Function

The strcmp() function compares two strings.

It returns:

• 0 if strings are equal
• Positive value if first string is greater
• Negative value if first string is smaller

strcat() Function

The strcat() function joins two strings.

char s1[20] = "Hello ";
char s2[] = "World";
strcat(s1, s2);

strncpy() and strncat()

These functions copy or concatenate a limited number of characters.

They help avoid buffer overflow issues.

Common Mistakes in String Handling

• Forgetting null terminator
• Using insufficient array size
• Not including string.h

String Input Using gets() and fgets()

gets() is unsafe and should be avoided.

fgets() is safer and recommended.

Interview Questions on Strings

• Difference between string and character array
• What does strcmp return?
• Why is gets unsafe?

Final Conclusion

String handling is a core concept in C programming. Mastering string functions will help you write real-world programs and crack interviews easily.

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