C function to remove vowels in a string not working?

Question

Here is my function to remove the vowels in a string;

char *removeVowels(char *inString) {

    int count = 0; //to count the non vowel characters

    for (int i = 0; inString[i]; i++)
        if (inString[i] != 'a' || inString[i] != 'e' || inString[i] != 'u' || inString[i] != 'o' || inString[i] != 'i')
            inString[count++] = inString[i]; //if character is not a vowel placed at count++  

    inString[count] = '';

    return inString;
}

The problem is that it is returning the original string inputted. Any ideas?

Answer 1

There is a confusion between the || and && operators. You want to test that the character is different from 'a' AND different from 'e' etc.

Here is a modified version:

char *removeVowels(char *inString) {
    int count = 0; // index for preserved characters

    for (int i = 0; inString[i]; i++) {
        if (inString[i] != 'a' && inString[i] != 'e' && inString[i] != 'i'
        &&  inString[i] != 'o' && inString[i] != 'u') {
            inString[count++] = inString[i]; // copy the non-vowel character
        }
    }
    inString[count] = '';  // set the null terminator.

    return inString;
}

Note however that uppercase vowels are not removed by this function, and whether y should be considered a vowel remains to be decided.