Conditionally executes code.
Used where code needs to be executed only if some condition is true.
[edit] Syntax attr-spec-seq (optional)if ( expression ) statement-true (1) attr-spec-seq (optional) if ( expression ) statement-true else statement-false (2) attr-spec-seq - (C23) an optional list of attributes, applied to the if statement expression - an expression of any scalar type statement-true - any statement (often a compound statement), which is executed if expression compares not equal to â0â statement-false - any statement (often a compound statement), which is executed if expression compares equal to â0â [edit] Explanation
expression must be an expression of any scalar type.
If expression compares not equal to the integer zero, statement-true is executed.
In the form (2), if expression compares equal to the integer zero, statement-false is executed.
As with all other selection and iteration statements, the entire if-statement has its own block scope:
enum {a, b};
int different(void)
{
if (sizeof(enum {b, a}) != sizeof(int))
return a; // a == 1
return b; // b == 0 in C89, b == 1 in C99
}(since C99) [edit] Notes
The else is always associated with the closest preceding if (in other words, if statement-true is also an if statement, then that inner if statement must contain an else part as well):
int j = 1;
if (i > 1)
if(j > 2)
printf("%d > 1 and %d > 2\n", i, j);
else // this else is part of if (j > 2), not part of if (i > 1)
printf("%d > 1 and %d <= 2\n", i, j);
If statement-true is entered through a goto, statement-false is not executed.
[edit] Keywords [edit] Example#include <stdio.h>
int main(void)
{
int i = 2;
if (i > 2)
{
printf("i > 2 is true\n");
}
else
{
printf("i > 2 is false\n");
}
i = 3;
if (i == 3)
printf("i == 3\n");
if (i != 3)
printf("i != 3 is true\n");
else
printf("i != 3 is false\n");
}
Output:
i > 2 is false i == 3 i != 3 is false[edit] References
RetroSearch is an open source project built by @garambo | Open a GitHub Issue
Search and Browse the WWW like it's 1997 | Search results from DuckDuckGo
HTML:
3.2
| Encoding:
UTF-8
| Version:
0.7.4