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if, else | Keywords |
Keyword Index |
Conditional statement.
Keyword if
is used for conditional execution. The basic form of if
uses the following syntax:
if (expression) statement1Alternatively,
if
may be used together with else
, using the
following syntax:
if (expression) statement1 else statement2If expression is nonzero when evaluated, then statement1 is executed. In the second case, statement2 is executed if the expression is 0.
else
can follow an if
statement, but no statements can come
between an if
statement and an else
. Of course, both
statement1 and statement2 may be compound statements (i.e. a sequence of
statements enclosed in braces). Here will be given some legal examples:
if (count < 50) count++; if (x < y) z = x; else z = y; if (x < y) { printf ("x is smaller"); return x; } else { printf ("x is greater") return y; }The #if and #else preprocessor statements look similar to the
if
and else
statements, but have very different effects.
They control which source file lines are compiled and which are ignored.