Strings in c

A string is not a formal data type like int or float. Instead, it is simply an array of characters that ends with a special character called the null terminator (\0).

The \0 tells C functions (like printf) where the text ends. Without it, the computer would keep reading memory until it crashes!

1. Declaration and Initialization

There are two main ways to create a string:

#include <stdio.h>

int main() {
    // Method 1: Array style (Size is automatically calculated as 6: 'H','e','l','l','o','\0')
    char greeting[] = "Hello"; 

    // Method 2: Pointer style (String literal)
    char *message = "Welcome to C";

    printf("%s, %s!\n", greeting, message);
    return 0;
}

Expected Output:

Hello, Welcome to C!

2. Reading Strings from the User

Reading strings can be tricky because scanf stops reading at the first space it encounters.

• scanf(): Good for single words.

• fgets(): The safest way to read a full line (including spaces).

#include <stdio.h>

int main() {
    char fullName[50];

    printf("Enter your full name: ");
    // fgets(variable, size, source)
    fgets(fullName, sizeof(fullName), stdin);

    printf("Hello, %s", fullName);
    return 0;
}

Expected Output:

Enter your full name: John Doe
Hello, John Doe

3. Standard String Functions (string.h)

To manipulate strings, you must include the <string.h> library. Here are the "Big Four" functions:

Function. Purpose. Example

strlen()Gets the length (excluding \0)strlen("Hi")

strcpy()Copies one string to anotherstrcpy(dest, src)strcat()Catenates (joins) two stringsstrcat(s1, s2)strcmp()Compares two stringsReturns 0 if they are identical.

code example:

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

int main() {
    char s1[20] = "Apple";
    char s2[20] = "Banana";

    // Compare
    if (strcmp(s1, s2) == 0) {
        printf("Strings are equal.\n");
    } else {
        printf("Strings are different.\n");
    }

    // Join
    strcat(s1, " Pie"); 
    printf("Result: %s\n", s1); // Prints "Apple Pie"

    return 0;
}

Expected Output:

Strings are different.
Result: Apple Pie