Practice Problems

Conditionals

Notice when you get compile errors (when gcc gives you an error)
vs. errors that crash the program (run-time errors)
vs. logical errors (compile and run fine but problem with your code)

  1. If originally x=4, y = 0, z = 2, what is the value of x, y, and z after the following code executes? 
    		if ( x != 0 )
			y = 3;
		else
			z = 2;
  2. If originally x=4, y = 0, z = 2, what is the value of x, y, and z after the following code executes? 
    		if ( z == 2 )
			y = 1;
		else
			x = 3;
  3. If originally x=4, y = 0, z = 2, what is the value of x, y, and z after the following code executes? 
    		if ( x && y )
			x = 3;
		else
			y = 2;
  4. If originally x=4, y = 0, z = 2, what is the value of x, y, and z after the following code executes? 
    		if ( x || y || z )
			y = 1;
		else
			z = 3;
  5. If originally x=4, y = 0, z = 2, what is the value of x, y, and z after the following code executes? 
    		if ( x && y )
			x = 3;
		else
			y = 2;
  6. If originally x=4, y = 0, z = 2, what is the value of x, y, and z after the following code executes? 
    		if ( x )
		   if ( y )
			z = 3;
		else
			z = 2;
  7. If originally x=0, y = 0, z = 1, what is the value of x, y, and z after the following code executes? 
    		if ( z < x || y >= z && z == 1)
		   if ( z && y )
			y = 1;
		else
			x = 1;
  8. If originally x=0, y = 0, z = 1, what is the value of x, y, and z after the following code executes? 
    		if ( z = x < y )
		{
			y = 5;
			z = -3;
		}
		else
			x = 2;
  9. If originally x=0, y = 0, z = 1, what is the value of x, y, and z after the following code executes? 
    		switch(x)
		{
			case 0 :  x = 2;
				  y = 3;
			case 1:	  x = 4;
			default:  y = 3;
				  x = 1;
		}


  10.  Rewrite the following code fragment using one switch statement
	
    		if ( ch == 'E' || ch == 'e' )
			countE = 1;
		else if ( ch == 'A' || ch == 'a' )
			countA = 1;
		else if ( ch == 'I' || ch == 'i' )
			countI = 1;
		else
			printf ("Error - not A, E, or I\n");
			countA = 1;
	
    

 
  11.  Write the code that reads in a number for month and prints
 	out the month as a string (e.g. 1 = January, 2 = February, ...)
	
    First implement as an if structure, then a switch
 
  12.  True/False. You can implement any switch statement in to
  an if-else structure.
 
  13.  True/False. You can implement any if-else statement in to
  a switch structure.
 
  14.   What is the numeric value of the expression 3 < 4 ?
 
  15.  Under what conditions will this code print ``water''?

    	if(T < 32)
		printf("ice\n");
	else if(T < 212)
		printf("water\n");
	else	printf("steam\n");

    

 
  16.  What would this code print?

    	int x = 3;
	if(x)
		printf("yes\n");
	else	printf("no\n");