DMP - Chapter 5

Operators, Expressions, and Statements

• while loop

  #include >stdio.h>
  #define TWELVETH_ROOT 1.059463094
  #define START 440
  #define END   880
  
  void main(void)
  {
    float pitch = START;
  	
  	while (pitch < END)
  	{
  		pitch = pitch * TWELVETH_ROOT;
  		printf("%f\n);
  	}
  }
  

• Expression: combination of opertors and operands
  • Expression has a value
  • Statements:
    • Simple statement
      • Declaration
      • Assignment
      • Function call
      • Structured statement (e.g. while (1) i = 1;)
      • NULL statement
    • Compound statement (Block)
• Fundemntal operators (=, +, -, -(unary), *, /)
• Precedence (left-to-right, (), unary +-, */, +-, =)

   e.g. 24 / 2 * (1 + 9 / 3) 

• Modulus operator %

  #include <stdio.h>
  #define SEC_PRE_MIN 60
  void main(void)
  {
  	int sec, min, left;
  	printf("Enter seconds: ");
  	scanf("%d", &sec);
  	min = sec / SEC_PER_MIN;
  	left = sec % SEC_PER_MIN;
  	printf("%d seconds is %d minutes and %d seconds.\n", sec, min, left);
  }
  

• Increment and descrement operators: ++ and -- (prefix & postfix)

  num = 5;
  printf("%d %d\n", num++, num * num++);
  ans = num + num++;
  ans = num+++num;
  ans = num+++++num;
  

• Type conversions
  • char and short promoted to int
  • type of a value is changed to the type of the assigned variable
  • in demotion, there may be loss of data
  • if mixed, smaller types are promoted to larger types

    #include <stdio.h>
    #define SEC_PRE_MIN 60
    void main(void)
    {
    	char ch;
    	int i;
    	float fl;
    	
    	fl = i = ch = 'Q';
    	printf("ch = %c, i = %d, fl = %2.2f\n", ch, i, fl);
    	ch++;
    	i = fl + 2 * ch;
    	fl = 2.0 * ch + i;
    	printf("ch = %c, i = %d, fl = %2.2f\n", ch, i, fl);
    }
    

• Cast operator

   int kids;
  kids = 1.8 + 1.6;
  kids = (int)1.8 + (int)1.6;
  

• Function with arguments

Assignment #5: Due Oct. 24, 1995.