concatenate two strings without standard library in C

To concatenate two strings without using the standard library in C, you can follow these steps:

Step 1: Declare two character arrays to store the strings you want to concatenate. Let's assume the first string is str1 and the second string is str2.

Step 2: Find the length of str1 and str2 using a loop that iterates until the null character ('\0') is encountered. This will help determine the length of the strings.

Step 3: Create a new character array to store the concatenated string. The size of this array should be equal to the sum of the lengths of str1 and str2 plus one extra character for the null character.

Step 4: Copy the characters from str1 to the new concatenated string array using a loop that iterates until the null character is encountered.

Step 5: Append the characters from str2 to the concatenated string array using another loop. Start from the position where str1 ends and iterate until the null character is encountered.

Step 6: Add a null character ('\0') at the end of the concatenated string array to mark the end of the concatenated string.

Here is an example code snippet that demonstrates the above steps:

#include <stdio.h>

void concatenateStrings(char str1, char str2, char* result) {
    int i, j;

    // Step 2
    for (i = 0; str1[i] != '\0'; i++) {
        result[i] = str1[i];
    }

    // Step 5
    for (j = 0; str2[j] != '\0'; j++) {
        result[i + j] = str2[j];
    }

    // Step 6
    result[i + j] = '\0';
}

int main() {
    char str1[] = "Hello";
    char str2[] = " World";
    char result[12]; // Size should be equal to the length of str1 + str2 + 1

    // Step 1
    concatenateStrings(str1, str2, result);

    printf("Concatenated string: %s\n", result);

    return 0;
}

In this example, the concatenateStrings function takes three arguments: str1, str2, and result. It performs the concatenation and stores the result in the result array.

The main function declares str1, str2, and result arrays. It then calls the concatenateStrings function to concatenate str1 and str2 and stores the result in the result array. Finally, it prints the concatenated string.

The output of the above code will be:

Concatenated string: Hello World

By following these steps, you can concatenate two strings without using the standard library in C.