Replacing characters in a string using pointers

Question

I'm supposed to make a program that replaces vowels in a string for numbers, without using and using pointers.

I used the commented printf in each switch statement to debug my program, and the output when the string is: aeiou, is:

4eiou
3iou
1ou
0u
2

and at the end when printing the string it just prints a blank line, when the output should be: 43102.

I'm doing something wrong that's replacing the complete string, but I can't figure it out. Can someone help me? Thank you very much!

#include <stdio.h>

void changes(char* ptr) {

    while (*ptr != '\0') {
        switch(*ptr) {
            case 'a':
                *(ptr)='4';
                //printf("%s\n", ptr);
                break;
            case 'e':
                *(ptr)='3';
                //printf("%s\n", ptr);
                break;
            case 'i':
                *(ptr)='1';
                //printf("%s\n", ptr);
                break;
            case 'o':
                *(ptr)='0';
                //printf("%s\n", ptr);
                break;
            case 'u':
                *(ptr)='2';
                //printf("%s\n", ptr);
                break;
            default: 
            break;
        }
        ptr++;
    }

    //Print the string
    printf("%s\n", ptr);
}

int main() {

    char sString[51];
    char *charPtr = NULL;

    charPtr = &sString[0];

    printf("Introduce a string: ");
    scanf("%[^\n]s", sString);

    changes(charPtr);
}

Format code as code please.

user202729
– user202729

2018-02-03 04:32:11 +00:00
Commented Feb 3, 2018 at 4:32 — user202729
– user202729, Commented Feb 3, 2018 at 4:32

user2736738 · Accepted Answer · 2018-02-03 04:38:38Z

1

You incrementing the pointer and printing what it points to using %s format specifier of printf. Keep a pointer to the beginning of the string and print it. You will see the desired behavior.

char *s = ptr;
while(*ptr != 0){

 ..
 printf("%s",s);
}

This will print the whole string.(And you can notice the changes that you have made).

edited Feb 3, 2018 at 4:38

answered Feb 3, 2018 at 4:28

user2736738

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1 Comment

Lorraine Over a year ago

This makes so much sense now! Thank you very much! I was definitely needing another head to help me find my mistake :)

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