String Manipulation in C

Strings are a fundamental data type in programming, used to represent sequences of characters. In the C programming language, strings are represented as arrays of characters terminated by a null character ('\0'). This tutorial will cover various string operations, including string input/output, concatenation, comparison, and manipulation.

1. Introduction to Strings

In C, strings are sequences of characters stored in an array. The last character of a string is always the null character ('\0'), which marks the end of the string.

2. String Declaration and Initialization

Strings can be declared and initialized using the following syntax:

char myString[] = "Hello, World!";

3. String Input and Output

C provides the printf() function for output and scanf() function for input. To print a string, you can use the %s format specifier:

#include 

int main() {
    char myString[] = "Hello, World!";
    printf("String: %s\n", myString);

    return 0;
}

To read a string, use the %s format specifier within scanf():

#include 

int main() {
    char inputString[100];
    printf("Enter a string: ");
    scanf("%s", inputString);
    printf("You entered: %s\n", inputString);

    return 0;
}

4. String Length

To find the length of a string, you can use the strlen() function from the string.h library:

#include 
#include 

int main() {
    char myString[] = "Hello, World!";
    int length = strlen(myString);
    printf("Length of string: %d\n", length);

    return 0;
}

5. String Concatenation

String concatenation involves combining two strings into a single string. This can be done using functions like strcat() from the string.h library or by manually iterating through the strings and copying characters.

#include 
#include 

int main() {
    char str1[50] = "Hello, ";
    char str2[] = "World!";
    
    strcat(str1, str2);
    
    printf("Concatenated string: %s\n", str1);

    return 0;
}

6. String Comparison

String comparison is performed using functions like strcmp() from the string.h library. It returns 0 if both strings are equal.

#include 
#include 

int main() {
    char str1[] = "apple";
    char str2[] = "orange";
    
    int result = strcmp(str1, str2);
    if (result == 0) {
        printf("Strings are equal.\n");
    } else {
        printf("Strings are not equal.\n");
    }

    return 0;
}

7. String Copying

To copy one string into another, you can use functions like strcpy() from the string.h library:

#include 
#include 

int main() {
    char source[] = "Copy this.";
    char destination[20];
    
    strcpy(destination, source);
    
    printf("Copied string: %s\n", destination);

    return 0;
}

8. String Manipulation

C provides various functions for manipulating strings, such as strchr(), strstr(), strtok(), etc. These functions help in searching for characters or substrings within a string, and tokenizing strings into smaller parts.