C语言中的向后递归打印

Question

I'm trying out recursion and tried this exercise to print a word backwords. What am i doing wrong?

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


void recursivePrint(char* x){

    if (*x = '\0')
        return;
    else
        recursivePrint(x++);
        printf("%c", *x);

}

int main()
{
    char x[10] = "Hello";

    recursivePrint(x);
    return 0;
}

Answer 1

= is an assignment operator. And == is used for comparison. Change

if (*x = '\0')

To

if (*x == '\0')

EDIT:

To see the first character,

Change

void recursivePrint(char* x){
    if (*x == '\0')
        return;
    else
        recursivePrint(x++);
    printf("%c", *x);
}

To

void recursivePrint(char* x){
    if (*x == '\0')
        return;
    else
        recursivePrint(x+1);
    printf("%c", *x);
}

Answer 2

Aside from the assignment that was meant to be a comparison (as pointed out in another answer), you shouldn't increment x , since you will want to output it after the recursive call. Incrementing x is unnecessary and as you can see is error-prone. What is happening is that the call number i is printing character i+1 , so the second to last call is actually passing the null terminator to printf() ; the third to last is passing the character before the NULL, etc. See it like this:

recursivePrint("Hello");
    recursivePrint("ello");
        recursivePrint("llo");
            recursivePrint("lo");
                recursivePrint("o");
                    recursivePrint("");
                        return;
                    /* x was incremented, points to \0 */
                    print '\0'
                /* x was incremented, points to "o" */
            /* ... */

So basically, you are always one character ahead of the one you want to print. You can fix it by passing x[-1] to printf() , but that is ugly. A better approach would be:

void recursivePrint(char *x) {
    if (*x == '\0')
        return;

    recursivePrint(x+1);
    printf("%c", *x);

}

This is better because you never wanted / needed to increment x in the first place.

Answer 3

Try this

void recursivePrint(char* x){
    if (*x == '\0')
        return;
    recursivePrint(x+1);
    printf("%c", *x);

}

Answer 4

You're close, but some of the answers here are incorrect and generate segfaults.

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

void recursivePrint(const char *x) {
   if (*x == '\0') {
      return;
   }
   recursivePrint(x+1);
   printf("%c", *x);
}

int main(void) {
   const char* x = "Hello";
   recursivePrint(x);
   return 0;
}

You should really use const char* since your function doesn't modify the data.