Project: Pointer Fun!

A project for CSCS 1320 by Paul Sechrist during the Spring 2013.

This project is to help learn about pointers, what they are used for, and how to use them.

#include <stdio.h>
#include <stdlib.h>
 
int main()
{
    char a, *b;
 
    a = 'a'; // what numeric value is being stored in the variable a? Why?
    b = &a;
 
    printf("a contains     '%c'\n", a);
    printf("a's address is 0x%X\n", &a);
    printf("-----------------------\n");
    printf("b dereferenced contains '%c'\n", *b);
    printf("b contains     0x%X\n", b);
    printf("b's address is 0x%X\n", &b);
 
    return(0);
}

#include <stdio.h>
#include <stdlib.h>
 
int main()
{
    char *a;
 
    a = (char *) malloc (sizeof(char));
 
    *a = 48;
 
    //fprintf(stdout, "*a is %c\n", *a);
 
    return(0);
}

1

#include <stdio.h>
#include <stdlib.h>
 
#define NUM_SCORES 5
#define SCORE0 87
#define SCORE1 92
#define SCORE2 97
#define SCORE3 83
#define SCORE4 79
 
int main()
{
    unsigned char *scores;
    float average;
 
    scores = (unsigned char *) malloc (sizeof(unsigned char) * NUM_SCORES);
    *(scores+0) = SCORE0;
    *(scores+1) = SCORE1;
    *(scores+2) = SCORE2;
    *(scores+3) = SCORE3;
    *(scores+4) = SCORE4;
 
    /* Please provide the equation to do average of the scores */
    //average = EQUATION TO DO AVERAGE
 
    /* Display the scores via array referencing and then the average.
     * %f can be used to display a floating point value. */
    //fprintf(stdout, "YOUR FORMATTED TEXT STRING", LIST OF VARIABLES);
 
    return(0);
}

• What do the variables a and b have in common?
• Where do they differ?
• If you change variable a, what will happen to b?
• If you change variable b, will it impact a?
• How can you change b without breaking things?

• If we uncomment that fprintf() line, what will be displayed?
• What is malloc() doing?
• Why is it needed?