C Tutorial



C Tutorial

If Statement in C


A key element of the C programming language is the "if" statement, which enables programs to decide what to do and control how their code runs in response to certain circumstances. This effective design enables code blocks to run only when specific requirements are met. We shall examine the usefulness of the "if" statement in C in this article. Additionally, we will give concrete examples to help with comprehension and analyze its benefits and drawbacks.

Programmers can build logical, effective programs that adapt intelligently to many conditions by understanding the complexities of the "if" statement in C. The "if" statement is a crucial component of structured and dynamic C programs because it allows for the implementation of branching logic and executes specified actions when certain conditions are fulfilled.

What does it mean in C?

The "if" statement is a control flow component of the C language. It enables the execution of several activities based on conditions. It is a key technique for developing decision-making programs in which particular code blocks are executed when a certain condition is met. Programmers can efficiently manage the flow of their code and take actions based on specified scenarios by using the "if" expression. 

The "if" statement offers the flexibility and control required to develop dynamic and responsive programs in the C programming language. It can carry out different code routes, create conditional branching, and selectively run code based on particular conditions.

The Syntax of the “if” Statement in C

The "if" statement in C has the following syntax:

if (condition)
    // Code block to be executed if the condition is true

The code block can only be evaluated if the condition is true. The code block is bypassed if the condition is false, and the program moves on to the statement that follows the "if'' block.

How to Use the if Statement in C?

In C language, take the following actions to use the "if" statement:

1. "If" is the first word you should use, then a space.

2. Put the condition between parentheses, which includes a simple expression or a string of expressions linked together by logical operators, such as “&&” for logical AND and “||” for logical OR.

3. If the condition is true, write the code block that will be executed in between the curly brackets.

4. The code block is finished when the curly brackets are closed.

To demonstrate how to use the "if" statement, consider the following example:

#include <stdio.h>
int main() {
    int number = 10;
    if (number > 0) {
        printf("The number is positive.\n");
   return 0;

The condition “number > 0” is tested in this example. The code block inside the "if" statement is run, and the message – "The number is positive." is printed if the value of the number is greater than 0.

How Does the “if” Statement Work in C?

The "if" statement's operation is described in detail below:

1. An evaluation of the condition is enclosed in brackets.

2. The "if" statement's accompanying code block is run if the condition is satisfied.

3. The code block is bypassed if the condition is false, and the program execution moves on to the statement that follows the "if" block.

It's significant to remember that the code block connected to the "if" expression may include more than one statement. Curly braces are optional if there is only one statement. Although, according to accepted best practices, curly brackets should always be used, even for a single sentence, to increase code readability and prevent future problems.

Flowchart of if in C

The above flowchart shows how control moves in an "if" expression. The program evaluates the condition and, depending on the outcome, either executes the code block linked to the "if" statement or moves on to the following statement.

Stack Operations in C

A stack is a data structure that adheres to the last-in-first-out (LIFO) concept. You can implement stack in C using arrays. You can also use stack in C using linked lists.

Let's investigate the standard stack operations in C:

Push and Pop in stack in C 

1. Push: When an element is pushed, it is added to the top of the stack. In an approach that uses an array, you increase the top variable and put the new element in the array at the appropriate index. Then a new node is created, the element is assigned to its data field, and the pointers are updated as necessary in a linked list implementation.

2. Pop: Using the pop command, the top element in the stack is removed. You access the element at the top index, decrease the top variable, and return the element in an array-based implementation. To implement a linked list, you change the top pointer to the subsequent node, release the memory of the node that was deleted, and then return the element.

Peek in stack in C

Peek helps to retrieve the top member of the stack without taking it out. You can access and return the element at the top index or the data field of the top node in implementations that use linked lists or arrays, respectively.

Examples of if Statements in C

Let's explore a few examples of "if" statements in C:

Example 1:

#include <stdio.h>
int main() {
    int age;
    printf("Enter your age: ");
    scanf("%d", &age);
    if (age >= 18) {
        printf("You are eligible to vote.\n");
    } else {
        printf("You are not eligible to vote.\n");
    return 0;

Here, the user is prompted by the program to enter their age. "You are eligible to vote." is displayed if the age is more than or equal to 18. If not, the warning "You are not eligible to vote." is shown.

Example 2:

#include <stdio.h>
int main() {
    int number;
    printf("Enter a number: ");
    scanf("%d", & number);
    if (number > 0) {
        printf("The number is positive.\n");
    } else if (number < 0) {
        printf("The number is negative.\n");
    } else {
        printf("The number is zero.\n");
    return 0;

In this illustration, the software asks the user to enter a number. Messages are shown in a variety of ways depending on the value of the number. The phrase "The number is positive." is presented if the result is positive. The phrase "The number is negative." is displayed if the value is negative. The phrase "The number is zero." appears if the value is zero.

Advantages of if Statement

The "if" statement in C has the following benefits:

1. Conditional Execution: Depending on the outcome of a condition, you can run particular code blocks conditionally using the "if" expression. This allows your program to decide what to do and take alternative actions based on various scenarios.

2. Flexibility: The "if" statement allows for using relational and logical operators to enable complicated conditions. With this versatility, you can express various criteria to meet your program's needs.

3. Control Flow: You may manage the flow of your program and choose which code blocks to run at different stages of execution by utilizing "if" expressions.

Disadvantages of if Statement

The "if" statement is a strong construction, but it also has significant drawbacks:

1. Nesting Complexity: Complexity of the nested "if" statements or other complex conditions might make the code challenging to read and comprehend. This makes it more difficult to maintain the code and can result in errors.

2. Code Duplication: You might want to run the same code block under several conditions. Without careful planning, this could lead to duplicate code, which increases the risk of errors and makes code maintenance more challenging.

3. Limited Scope: The "if" statement has a narrow range of use. It can only evaluate one situation at a time and make judgments based on that evaluation. Use alternative control flow constructs like "switch" statements or nested "if" statements if you need to handle many circumstances concurrently or make more sophisticated decisions.


The "if" statement is incredibly important in the C programming language. It helps you make your program work under certain circumstances. It is essential to master the syntax, use, and underlying logic of the "if" statement to write intelligent C programs that can respond to various scenarios.


1. How can I use an array to implement a stack in C?

To implement a stack in C using an array, define an array to hold the stack's components and keep track of the stack's top with a variable. Based on the array and the top variable, push and pop operations may be implemented. This method offers a quick and effective technique to set up a stack.

2. How can I implement stack in C using linked lists?

To implement stack in C, you can define a structure representing a node in the linked list as an alternative to an array. The data element and a pointer to the following node may be included in each node. You can manipulate the linked list structure by performing push and pop operations by keeping a pointer to the top of the stack.

3. How can I have access to the top element of a stack in C?

In C, you can use the "peek" technique to get to the top element of a stack. Without removing it, the element at the top of the stack is examined during the "peek" operation. You can access the element at the top index in an implementation of a stack-based on an array. You can get to the data element of the top node in a stack implementation based on a linked list.

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