Review questions for COSC 341 Exam:  C language

1. Consider this C program

/* compute and output prefix sums */

#include <stdio.h>

void printArray(int a[], int size) {
    int i;
    for (i = 0; i < size; i++) {
        printf("%d ", a[i]);
    }
    printf("\n");
}

int main() {
    int i;
    int a[] = {1, 2, 3, 4, 5};

    int number = (sizeof a) / sizeof(int);
    int c[number];

    c[0] = a[0];
    for (i = 1; i < number; i++) {
        c[i] = c[i-1] + a[i];
    }

    printf("prefix sum: ");
    printArray(c, number);

    return 0;
}


1.a. What is the output?

1.b.  Modify this code to do the following:
    Add an array b[] with values {10, 20, 30, 40, 50}
    Compute array c[] -- the values of each c element is the sum of corresponding
      values of a[] and b[]
    Output array c[]
    
1.c. Suppose you change the original code line 
  int a[] = {1, 2, 3, 4, 5};

to
  int a[] = {1, 2, 3};
  
Will the resulting program still compute prefix sum?


1.d.  You comment (explain) the line of code
  int number = (sizeof a) / sizeof(int);
  
  What is your comment?
  
  
2. Given the operator precedence/associativity (http://www.swansontec.com/sopc.html)
fully parenthesize the following expressions to explicitly show the order of
operations. Ignore type.

Example:
  3 + 2 + 5 * 6 * 7  -->  (3 + 2) + ((5 * 6) * 7)
  
y = x << 3 * x & 8

y = x = count + 7

++i++

p -> next -> data

x < 3 || y >>3 > 2


3. Consider this sequence of declarations and assignments in C

int   a, b, c
int   *p, *q, *r;
int   **s;

a = 10;
b = 20;
p = &a;
q = &b;
r = p;

c = *p * *q;
*r = *q;

s = &q;
**s = 30;

What are values of a, b, c?