Sams Teach Yourself C in 21 Days

The Pieces of a C Program: Statements, Expressions, and Operators 75

4

13: printf(“\nInput an integer value for y: “);

14: scanf(“%d”, &y);

15:

16: /* Test values and print result */

17:

18: if (x == y)

19: printf(“x is equal to y\n”);

20:

21: if (x > y)

22: printf(“x is greater than y\n”);

23:

24: if (x < y)

25: printf(“x is smaller than y\n”);

26:

27: return 0;

28: }

Input an integer value for x: 100

Input an integer value for y: 10

x is greater than y

Input an integer value for x: 10

Input an integer value for y: 100

x is smaller than y

Input an integer value for x: 10

Input an integer value for y: 10

x is equal to y

List0403.c shows three ifstatements in action (lines 18 through 25). Many of

the lines in this program should be familiar. Line 5 declares two variables,xand

y, and lines 11 through 14 prompt the user for values to be placed into these variables.

Lines 18 through 25 use ifstatements to determine whether xis greater than, less than,

or equal to y. Note that line 18 uses an ifstatement to see whether xis equal to y.

Remember==, the equal operator, means “is equal to” and should not be confused with

=, the assignment operator. After the program checks to see whether the variables are

equal, in line 21 it checks to see whether xis greater than y, followed by a check in line

24 to see whether xis less than y. If you think this is inefficient, you’re right. In the next

program, you will see how to avoid this inefficiency. For now, run the program with dif-

ferent values for xandyto see the results.

LISTING4.3 continued

INPUT/

OUTPUT

ANALYSIS

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