C Statement Types (for
Structured Programming)
| Type |
Syntax |
Example |
Semantics |
| null |
;
|
;
|
Does nothing semantically |
| expression |
<expression> ;
|
x=4;
|
The <expression> is evaluated |
| compound |
{ <statement list> }
|
{x=4; y='A';}
|
The <statement list> is executed in sequence. |
| while |
while ( <expression> )
<statement>
|
while (x < 10)
x += 1;
|
The <statement> is executed as long as the
<expression> is true (non-zero). |
| do |
do <statement>
while ( <expression> );
|
do a[i] = b[i]
while (i < 10);
|
The <statement> is repeated as long as the
<expression> is true (non-zero). |
| for |
for ( <expression 1>;
<expression 2>;
<expression 3>)
<statement>
|
for (i = 0; i < 10; ++i)
a [i] = b [i];
|
Equivalent to:
<expression 1>;
while (<expression 2>) {
<statement>
<expression 3>;
}
|
| return |
return <expression>;
|
return status;
|
Control is returned to the calling statement, and the
<expression>
is evaluated, and its value is returned as the value of the
function. |
return;
|
return;
|
Control is returned to the calling statement. This form
of the return statement can only be used within a function
having a void (return) type. |
| if |
if ( <expression> )
<statement>
|
if (x < 0)
x = -x;
|
The
<expression>
is evaluated. If it is true (non-zero), the
<statement>
is executed. |
| if-else |
if ( <expression> )
<statement 1>
else
<statement 2>
|
if (x < 0)
x = -x;
else
y = 4;
|
The
<expression>
is evaluated. If it is true (non-zero), the
<statement 1>
is executed. If it is false (zero), the
<statement 2>
is executed. |
| switch |
switch ( <expression> )
( <case list> }
where
<case list>
is a sequence of
case <value>: <statement list>
break;
and optionally one
default: <statement list>
break;
|
switch (key) {
case 'A': state = 1;
break;
case 'B': state = 2;
break;
default: state = 0;
break;
}
|
The
<expression>
is evaluated. Its value is then compared to each case
<value>. If it is equal, the
<statement list>
following that case is executed. (Each value must
appear at most once.) If none of the case
<value>s is equal to the expression value, the
<statement list>
following a default: is executed. |
C Statement Types (for
Unstructured Programming)
| Type |
Syntax |
Example |
Semantics |
| labeled |
<label>: <statement>
|
loop: x = x + 1;
|
Provides a placemarker for goto statements. |
| go to |
goto <label>;
|
goto loop;
|
Control is transferred to the statement with the designated
label. |
| break |
break;
|
break;
|
Control is transferred to the statement following the compound
statement within which the break appears. |
| continue |
continue;
|
continue;
|
Control is transferred to the point following the last
statement within the compound statement within which the
continue appears. |
| switch |
switch ( <expression> )
( <case list> }
where
<case list>
is a sequence of
case <value>: <statement list>
and optionally one
default: <statement list>
|
switch (key) {
case 'A': state = 1;
case 'B': state = 2;
default: state = 0;
}
|
The
<expression>
is evaluated. Its value is then compared to each case
<value>. If it is equal, control is transferred to the
<statement list>
following that case. (Each value must appear at most
once.) If none of the case <value>s is equal to
the expression value, control is transferred to the
<statement list>
following a default:. |
