An expression is a combination of operands and operators that produces a value. A statement is a complete instruction that controls execution or performs an operation.
#include <stdio.h>
int main()
{
int a = 10;
int b = 20;
a + b;
a = a + b;
printf("%d\n", a);
return 0;
}Example Output #
30Explanation #
The expression:
a + bproduces the value 30, but the result is not used.
The expression:
a = a + bcontains an addition expression and an assignment operation. The resulting value is assigned to a.
A semicolon turns an expression into an expression statement:
a + b;C also has other types of statements, including compound statements, selection statements, iteration statements, and jump statements.
Basic Statement Categories #
| Category | Examples | Purpose |
|---|---|---|
| Expression statement | a = 10; |
Evaluates an expression |
| Compound statement | { ... } |
Groups multiple statements |
| Selection statement | if, switch |
Selects execution paths |
| Iteration statement | while, do, for |
Repeats statements |
| Jump statement | break, continue, goto, return |
Transfers control |
Expressions and Statements #
| Expression | Statement |
|---|---|
| Produces a value or designates an object/function | Represents a complete executable construct |
| Can be part of a larger expression | Can contain one or more expressions |
Example: a + b |
Example: a = a + b; |
Does not necessarily end with ; |
An expression statement ends with ; |
A compound statement is a block enclosed by braces:
{
int number = 10;
printf("%d\n", number);
}The declarations and statements inside the braces form a single compound statement.
