Table of Contents
C syntax defines how declarations, expressions, statements, functions, and blocks are written. The following example combines the basic syntax used throughout a C program.
#include <stdio.h>
int add(int a, int b)
{
return a + b;
}
int main(void)
{
int number = 10;
if (number > 0)
{
printf("Positive\n");
}
printf("Sum = %d\n", add(number, 20));
return 0;
}Example Output #
Positive
Sum = 30Explanation #
The main syntax elements in the example are:
| Syntax | Example | Purpose |
|---|---|---|
| Header inclusion | #include <stdio.h> |
Includes a header |
| Function definition | int add(int a, int b) |
Defines a function |
| Parameter declaration | int a |
Declares a function parameter |
| Block | { ... } |
Groups declarations and statements |
| Variable declaration | int number; |
Declares an object |
| Initialization | int number = 10; |
Declares and initializes an object |
| Function call | add(number, 20) |
Calls a function |
| Conditional statement | if (number > 0) |
Conditionally executes a block |
| Expression | number > 0 |
Produces a value |
| Statement terminator | ; |
Terminates declarations and expression statements |
| Return statement | return 0; |
Returns a value from a function |
| Comment | /* comment */ |
Adds source-code documentation |
Common Syntax Rules #
Statements normally end with a semicolon:
int number = 10;
number = 20;
printf("%d\n", number);Blocks use braces:
if (number > 0)
{
printf("Positive\n");
}Identifiers are case-sensitive:
int value;
int Value;value and Value are different identifiers.
Strings use double quotes:
printf("Hello\n");Character constants use single quotes:
char letter = 'A';Keywords cannot be used as identifiers:
int return; /* Invalid */These rules form the basic syntax used by the later C language features.
