Reverse string array

Question

I'm trying to reverse an array of characters and place it in a new array. It doesn't seem to be returning anything. Here is the code below, I can't figure out waht is wrong. Any pointers? (No pun intended)

void getReverse(char dest[], char src[])
{
    int i;
    int j=0; 
    int length = strlen(src);
    printf("%d\n", length);

    for(i=length-1; i>=0; i--, j++)
        //for(j=0; j<length; j++)
        {
            dest[j]=src[i];
            putchar(j);
            j++;
        }
        dest[j] = '\0';
}

main()
{
    char dest[MAX_SIZE];
    char src[MAX_SIZE];
    int i = 0;
    int count;
    int c = getchar();

    count = 0;

    while ((count < MAX_SIZE) || (c != EOF))
    {
        src[count] = c;
        ++count;
        //putchar(c);
        c = getchar();  

    }

    getReverse(dest, src);
    printf("%s", dest);     
}

Answer 1

bugs:

1. as @Bill said, j++ execute in the loop of getReverse() twice.

2. the putchar(j) in getReverse() will lead to a confused output, as j is very little they may be unprintable character. If you really want to monitor the value of j, use printf("%d\\n",j);

3. as @jarmod said ,you miss a '\\0' in src[]. You should add "src[count] = '\\0';" after the loop of while() and before getReverse() in main().

in addition,your getReverse() can't work if *src and *dest point to the same address.Althogh you have declared that the function "reverse an array of characters and place it in a new array", but consider this when you write a more common function.

Answer 2

I just modify some code and run it. the code as follow

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

#define MAX_SIZE 30

void getReverse(char dest[], char src[])
{
    int i;
    int j=0;
    int length = strlen(src);
    printf("%d\n", length);

    for(i=length-1; i>=0; i--, j++)
    //for(j=0; j<length; j++)
    {
        dest[j]=src[i];
        //putchar(j);
        //j++;
    }
    dest[j] = '\0';
}

main()
{
    char dest[MAX_SIZE];
    char src[MAX_SIZE];
    int i = 0;
    int count;
    int c = getchar();

    count = 0;

    memset(src, 0, MAX_SIZE);

    while ((count < MAX_SIZE - 1) && c != EOF)
    {
        src[count] = c;
        ++count;
        //putchar(c);
        c = getchar();  

    }

    printf("src=%s\n", src);

    getReverse(dest, src);
    printf("dest=%s\n", dest);     
}

the result as follow

abcdefghijk
src=abcdefghijk
11
dest=kjihgfedcba

Answer 3

Here the value of j incremented twice.

for(i=length-1; i>=0; i--, **j++**)
        //for(j=0; j<length; j++)
        {
            dest[j]=src[i];
            putchar(j);
            **j++**;
        }
        dest[j] = '\0';
}

This may be the problem.

Answer 4

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

void getReverse(char dest[], char src[])
{
    int i;
    int j=0; 
    int length = strlen(src);
    printf("%d\n", length);

    for(i=length-1; i>=0; i--, j++)
        //for(j=0; j<length; j++)
        {
            dest[j]=src[i];
            //putchar(dest[j]);
            //j++;//duplicate , `for` after expression
        }
        dest[j] = '\0';
}

#define MAX_SIZE 32

int main(void){
    char dest[MAX_SIZE];
    char src[MAX_SIZE];
    //int i = 0;//unused
    int count;
    int c = getchar();

    count = 0;

    while ((count < MAX_SIZE) && (c != EOF))//|| -> &&
        if(c == '\n'){
            src[count] = '\0';
            break;
        }
        src[count] = c;
        ++count;
        //putchar(c);
        c = getchar();  

    }

    getReverse(dest, src);
    printf("%s", dest);
    return 0;
}