if in C++

By: Stanley B. Emailed: 1748 times Printed: 2432 times    

Latest comments
By: rohit kumar - how this program is work
By: Kirti - Hi..thx for the hadoop in
By: Spijker - I have altered the code a
By: ali mohammed - why we use the java in ne
By: ali mohammed - why we use the java in ne
By: mizhelle - when I exported the data
By: raul - no output as well, i'm ge
By: Rajesh - thanx very much...
By: Suindu De - Suppose we are executing

A logical extension of summing the values between 1 and 10 is to sum the values between two numbers our user supplies. We might use the numbers directly in our for loop, using the first input as the lower bound for the range and the second as the upper bound. However, if the user gives us the higher number first, that strategy would fail: Our program would exit the for loop immediately. Instead, we should adjust the range so that the larger number is the upper bound and the smaller is the lower. To do so, we need a way to see which number is larger.

Like most languages, C++ provides an if statement that supports conditional execution. We can use an if to write our revised sum program:

#include <iostream>
int main()
{
std::cout << "Enter two numbers:" << std::endl;
int v1, v2;
std::cin >> v1 >> v2; // read input
// use smaller number as lower bound for summation
// and larger number as upper bound
int lower, upper;
if (v1 <= v2) {
lower = v1;
upper = v2;
} else {
lower = v2;
upper = v1;
}
int sum = 0;
// sum values from lower up to and including upper
for (int val = lower; val <= upper; ++val)
sum += val; // sum = sum + val

std::cout << "Sum of " << lower
<< " to " << upper
<< " inclusive is "
<< sum << std::endl;
return 0;
}

If we compile and execute this program and give it as input the numbers 7 and 3, then the output of our program will be

Sum of 3 to 7 inclusive is 25

Most of the code in this program should already be familiar from our earlier examples. The program starts by writing a prompt to the user and defines four int variables. It then reads from the standard input into v1 and v2. The only new code is the if statement

// use smaller number as lower bound for summation
// and larger number as upper bound
int lower, upper;
if (v1 <= v2) {
lower = v1;
upper = v2;
} else {
lower = v2;
upper = v1;
}

The effect of this code is to set upper and lower appropriately. The if condition tests whether v1 is less than or equal to v2. If so, we perform the block that immediately follows the condition. This block contains two statements, each of which does an assignment. The first statement assigns v1 to lower and the second assigns v2 to upper.

If the condition is falsethat is, if v1 is larger than v2then we execute the statement following the else. Again, this statement is a block consisting of two assignments. We assign v2 to lower and v1 to upper.


C++ Home | All C++ Tutorials | Latest C++ Tutorials

Sponsored Links

If this tutorial doesn't answer your question, or you have a specific question, just ask an expert here. Post your question to get a direct answer.



Bookmark and Share

Comments(0)


Be the first one to add a comment

Your name (required):


Your email(required, will not be shown to the public):


Your sites URL (optional):


Your comments:



More Tutorials by Stanley B.
Enumerations in C++
typedef in C++
Declarations and Definitions in C++
Uninitialized Variables Cause Run-Time Problems in C++
C++ keywords
Lvalues and Rvalues in C++
Multi-Line Literals in C++
Concatenated String Literals in C++
Character String Literals in C++
Escape Sequences for Nonprintable Characters in C++
Using the Built-in Arithmetic Types in C++
if in C++
Programming errors a compiler will detect in C++
for loop in C++
while loop in C++

More Tutorials in C++
Two-Dimensional Array Manipulation in C++
Calculate average using Two-Dimensional Array in C++
Compute the square root of the sum of the squares of an array in C++
Matrix using nested for loops in C++
Sorting an array of Strings in C++
Calculating total based on the given quantity and price in C++
Compiling and Linking Multiple Source Files in C++
Enumerations in C++
Program to add two numbers in C++
Comments in C++
while loop in C++
for loop in C++
Programming errors a compiler will detect in C++
if in C++
Using the Built-in Arithmetic Types in C++

More Latest News
Most Viewed Articles (in C++ )
Difference between Procedural, Structured, and Object-Oriented Programming
assert() example program in C++
Dot (.) vs Arrow (->) to access data members in C++
Constructors and Destructors in C++
Using cout in C++
while (1) Loops in C++
for loop in C++
Calculate average using Two-Dimensional Array in C++
Calculating total based on the given quantity and price in C++
Using Comments in a C++ Program
class keyword in C++
Converting Pointer Parameters in C++ to Java
Converting Default Function Arguments in C++ to Java
Operator Precedence in C++
Using cout.width() in C++
Most Emailed Articles (in C++)
const Member Functions in C++
Printing values in DEBUG mode in C++
if in C++
Returning values from a function in C++
Public versus Private members in C++
atoi(), itoa() in C++
qsort() sample program in C++
Pass by Reference in C++ functions
Pass by Reference vs Pass Value in C++ functions
Demonstration of Prefix and Postfix operators in C++
Where to Put Class Declarations and Method Definitions in C++
continue and break statements in C++
C ++ Reference Parameters Versus Java Reference Parameters
Getting User Input Using cin in C++
Function overloading in C++