A statement in a general sense is a part of your program that can be executed i.e., a statement specifies an action.
Table of Contents
Statement in C is categorized into the following groups:
- Selection or Conditional statement
- Iteration or Loop statement
- Jump
- Expression
- Block
In this article, we will discuss the Conditional Statement or Selection statement and Jump statement in depth.
So let’s discuss the above topics in brief here and then we will continue with the if statement in C.
Block Statements
- Block statements are simply blocks of code. A block begins with { and ends with a }.
- Block statements are also referred to as compound statements.
Expression Statements
- Expression statements are composed of a valid expression or can say that this is a combination of operators and operands which reduces to a single value followed by a semicolon (;).
- Eg:
i = 0; i = i + 1;
Iteration or Loop statement
- The iteration statements are for, while, and do-while. These are also commonly called loop statements.
- Iteration statements cause statements to be executed zero or more times depending upon the conditions except when either the break statement or the continue statement is encountered.
- We will discuss the loop in detail in upcoming articles.
Selection or Conditional statement
if statement in C and the switch statement are the two selection statements. In addition, the conditional operator ( ? : ) is an alternative to the if statement in C under certain circumstances.
if statement in C
The general form of the if statement is
if( expression)
{
statement;
statement1;
statement2;
.
.
.
}
else
{
statement;
statement1;
}
- if expression evaluates to true (anything other than 0), the statement or block that forms the target of if is executed; otherwise, the statement or block that is the target of else will be executed, if it exists.
- Either the code associated with if or the code associated with else executes, never both.
Let’s have a very simple C program to see the working of if
WAP to enter a number and check if it is positive or negative.
#include <stdio.h>
void main()
{
int n;
printf("Enter a number \n");
scanf("%d", &n);
if (n >= 0)
printf("%d is a positive number \n", n);
else
printf("%d is a negative number \n", n);
}
Code Explanation
- I have taken an integer which I want to check as input from the user and store it in a variable n.
- Using if, else statements I have checked whether the integer is greater or lesser than zero( as we all know that if a number is greater than 0 then it is positive else negative)
- If it is greater than or equal to zero, then print the output as “Number is positive number”.
- If it is lesser than zero, then print the output as “Number is negative number”.
- Exit.
Nested if-else statement in C
- Nesting means if inside if block or else inside else block.
- Repetition can take place n number of times.
if(condition/expression)
{
//Nesting of if else inside the body of "if"
if(condition/expression)
{
//Statements inside the body of nested "if"
}
else
{
//Statements inside the body of nested "if"
}
}
else
{
//Nesting of if else inside the body of "else"
if(condition/expression)
{
//Statements inside the body of nested "else"
}
else
{
//Statements inside the body of nested "else"
}
}
Example of nested if..else statement
#include <stdio.h>
int main()
{
int n, m;
printf("Input the value of n:");
scanf("%d", &n);
printf("Input the value of m:");
scanf("%d",&m);
if (n != m)
{
printf("%d is not equal to %d\n", n, m);
//Nested if else
if (n > m)
{
printf("%d is greater than %d \n", n, m);
}
else
{
printf("%d is greater than %d\n", m, n);
}
}
else
{
printf("%d is equal to %d\n", n, m);
}
return 0;
}
Output:
Input the value of n:15
Input the value of m:12
15 is not equal to 12
15 is greater than 12
C – else..if statement
This statement is used when you have to check multiple conditions. We can use this and avoid the use of the nesting if-else statement.
Syntax of else..if statement:
if (condition/expression1)
{
//This statements will execute if the condition1 is true
}
else if(condition/expression2)
{
//This statements will execute if thecondition2 is true
}
else if (condition/expression3)
{
//This statements will execute if the condition3 is true
}
.
.
.
.
.
else
{
//This statements will execute if the conditions return false.
}
Example of else..if statement
Let’s take the above example we have seen above and will rewrite the same program using else…if statements.
#include <stdio.h>
int main()
{
int n, m;
printf("Input the value of n:");
scanf("%d", &n);
printf("Input the value of m:");
scanf("%d",&m);
if (n != m)
{
printf("%d is not equal to %d\n", n, m);
}
else if (n > m)
{
printf("%d is greater than %d \n", n, m);
}
else if (m > n)
{
printf("%d is greater than %d\n", m, n);
}
else
{
printf("%d is equal to %d\n", n, m);
}
return 0;
}
Output:
Input the value of n:15
Input the value of m:12
15 is not equal to 12
Conditional operator (? 🙂
We have covered conditional operator? : or also known as a ternary operator which can be used to replace if…else statements under the following circumstances. Its general form is −
Exp1 ? Exp2 : Exp3;
Where Exp1, Exp2, and Exp3 are expressions.
Click here for Operators in details
The value of conditional statement/expression is determined like this −
- Exp1 is evaluated first and if it is true, then Exp2 is evaluated and becomes the value of the entire expression.
- if Exp1 is false, then Exp3 is evaluated and its value becomes the value of the expression.
Let’s have an example of the conditional operator
#include <stdio.h>
int main()
{
int age; // variable declaration
printf("Enter your age");
scanf("%d",&age); // user input for age variable
(age>=18)? (printf("eligible for voting")) : (printf("not eligible for voting")); // conditional operator
return 0;
}
Output
Enter your age 18
18
eligible for voting
Enter your age 17
17
not eligible for voting
I hope you will find this information useful. If you have any queries in the if statement in C, please comment below or you can contact me directly.