Control Structures in C
Control structures are essential for controlling the flow of execution in a C program. They allow you to make decisions (conditional statements) and repeat actions (looping structures).
1. Conditional Statements
a. if Statement
The if statement is used to execute a block of code if a specified condition is true.
Syntax
if (condition) {
// code to be executed if the condition is true
}Example
#include <stdio.h>
int main() {
int a = 5;
if (a > 0) {
printf("a is positive.\n");
}
return 0;
}b. else Statement
The else statement provides an alternative block of code to execute if the condition in the if statement is false.
Syntax
if (condition) {
// code to be executed if the condition is true
} else {
// code to be executed if the condition is false
}Example
#include <stdio.h>
int main() {
int a = -5;
if (a > 0) {
printf("a is positive.\n");
} else {
printf("a is non-positive.\n");
}
return 0;
}c. switch Statement
The switch statement is used to execute one block of code among many options based on the value of a variable.
Syntax
switch (expression) {
case constant1:
// code to be executed if expression == constant1
break;
case constant2:
// code to be executed if expression == constant2
break;
default:
// code to be executed if none of the constants match
}Example
#include <stdio.h>
int main() {
int day = 3;
switch (day) {
case 1:
printf("Monday\n");
break;
case 2:
printf("Tuesday\n");
break;
case 3:
printf("Wednesday\n");
break;
default:
printf("Invalid day\n");
}
return 0;
}2. Looping Structures
a. for Loop
The for loop is used to execute a block of code a specific number of times.
Syntax
for (initialization; condition; increment/decrement) {
// code to be executed
}Example
#include <stdio.h>
int main() {
for (int i = 0; i < 5; i++) {
printf("%d\n", i);
}
return 0;
}b. while Loop
The while loop repeatedly executes a block of code as long as a specified condition is true.
Syntax
while (condition) {
// code to be executed
}Example
#include <stdio.h>
int main() {
int i = 0;
while (i < 5) {
printf("%d\n", i);
i++;
}
return 0;
}c. do-while Loop
The do-while loop is similar to the while loop, but it guarantees that the block of code is executed at least once.
Syntax
do {
// code to be executed
} while (condition);Example
#include <stdio.h>
int main() {
int i = 0;
do {
printf("%d\n", i);
i++;
} while (i < 5);
return 0;
}Diagram of Control Structures in C
Summary of Control Structures in C
-
Conditional Statements:
if: Executes code if the condition is true.else: Executes alternative code if the condition is false.switch: Executes code based on the value of a variable.
-
Looping Structures:
for: Repeats code a specific number of times.while: Repeats code as long as the condition is true.do-while: Repeats code at least once, checking the condition afterward.
Understanding these control structures is crucial for implementing logic in C programs.
Key Points:
- Conditional statements allow for decision-making in code.
- Looping structures enable repeated execution of code blocks based on certain conditions.