How do I parse a string in C?

Question

I am a beginner learning C; so, please go easy on me. :)

I am trying to write a very simple program that takes each word of a string into a "Hi (input)!" sentence (it assumes you type in names). Also, I am using arrays because I need to practice them.

My problem is that, some garbage gets putten into the arrays somewhere, and it messes up the program. I tried to figure out the problem but to no avail; so, it is time to ask for expert help. Where have I made mistakes?

p.s.: It also has an infinite loop somewhere, but it is probably the result of the garbage that is put into the array.

#include <stdio.h>
#define MAX 500 //Maximum Array size.

int main(int argc, const char * argv[])
{
    int stringArray [MAX];
    int wordArray [MAX];
    int counter = 0;
    int wordCounter = 0;

    printf("Please type in a list of names then hit ENTER:\n");  
    // Fill up the stringArray with user input.
    stringArray[counter] = getchar();
    while (stringArray[counter] != '\n') {
        stringArray[++counter] = getchar();
    }

    // Main function.
    counter = 0;
    while (stringArray[wordCounter] != '\n') {     
        // Puts first word into temporary wordArray.
        while ((stringArray[wordCounter] != ' ') && (stringArray[wordCounter] != '\n')) {
            wordArray[counter++] = stringArray[wordCounter++];
        }
        wordArray[counter] = '\0';

        //Prints out the content of wordArray.
        counter = 0;
        printf("Hi ");
        while (wordArray[counter] != '\0') {
            putchar(wordArray[counter]);
            counter++;
        }
        printf("!\n");

        //Clears temporary wordArray for new use.
        for (counter = 0; counter == MAX; counter++) {
            wordArray[counter] = '\0';
        } 
        wordCounter++;
        counter = 0; 
    }
    return 0;
}

Solved it! I needed to add to following if sentence to the end when I incremented the wordCounter. :)

    if (stringArray[wordCounter] != '\n') {
            wordCounter++;
    }

Answer 1

You are using int arrays to represent strings, probably because getchar() returns in int. However, strings are better represented as char arrays, since that's what they are, in C. The fact that getchar() returns an int is certainly confusing, it's because it needs to be able to return the special value EOF, which doesn't fit in a char. Therefore it uses int, which is a "larger" type (able to represent more different values). So, it can fit all the char values, and EOF.

With char arrays, you can use C's string functions directly:

char stringArray[MAX];

if(fgets(stringArray, sizeof stringArray, stdin) != NULL)
   printf("You entered %s", stringArray);

Note that fscanf() will leave the end of line character(s) in the string, so you might want to strip them out. I suggest implementing an in-place function that trims off leading and trailing whitespace, it's a good exercise as well.