how to reverse string in array in C

Question

I have exercise to use for loop to initialization 1 string array from A to Z and then Z to A.

I was successful to print from A to Z but print Z to A not working. So i need to help in this code.

char *problem58()
{
    char temp, *result = (char *)malloc(52 * sizeof(char));
    int left = 0, right = 52 - 1;

    for (char i = 'A'; i <= 'Z'; i++)
    {
        result[left] = i;
        printf("%c", i);
        left++;
    }
    // this is my idea to reverse this string
    for (int i = left; i < right; i++)
    {
        temp = result[left];
        result[left] = result[right];
        result[right] = temp;
        printf("%c", result[right]);
        right--;
    }
    return result;
}

line code run in terminal: ABCDEFGHIJKLMNOPQRSTUVWXYZSW\:C=cepSmoC

Answer 1

Here is my answer

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

char* problem58()
{
    int n = 0;
    int left = 0, right = 52 - 1;

    // A--->Z and Z--->A total number is 52, because string end with '\0'(0), so add 1 is 53.
    char* result = (char*)malloc(53 * sizeof(char));

    // Check if it is possible to dynamically allocate memory for 53 variables of type "char"
    // You can also write like this: if(result == NULL)
    if(NULL == result){
        printf("No space\n");
        exit(1);
    }

    // Initial result with 0,because string end with ('\0')0.
    // So result[0] will be 0, result[1] will be 0 ...... result[52] will be 0
    for(int m = 0; m < 53;m++){
        result[m] = 0;
    }

    for (char i = 'A'; i <= 'Z'; i++)
    {
        result[left] = i;
        //printf("%c", i);
        left++;
    }

    // Now left is 26, reset it to 0, because result[0] is 'A'
    left = 0;

    // n is execute times, need to let result[51] = result[0] = 'A', and result[50] = result[1] = 'B' ......
    //so right-- and left++
    for (n = 0; n < 26; n++)
    {
        result[right] = result[left];
        right--;
        left++;
    }
    return result;
}

int main()
{

    char* str = problem58();
    printf("str's length is %ld\n",strlen(str));
    printf("%s\n",str);
    free(str);
    return 0;
}

Run it will output

str's length is 52
ABCDEFGHIJKLMNOPQRSTUVWXYZZYXWVUTSRQPONMLKJIHGFEDCBA