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nested if else

Lee125 (67)
hello. I'm confuse with these two program.
why there is difference when put the braces in nested if else statement?
Output for program A is difference from program B.


programA

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#include <iostream>
using namespace std;

int main() {
	int marks, band;

	cout << "Enter your marks: ";
	cin >> marks;

band = 1;
if (marks > 50) 
{
if (marks < 75)
band = 2;	
} 
else
band = 3;

	cout << "You are in band " << band << endl;

    system("PAUSE");  // for Dev C++ 
	return 0;
}



sample input: 80 60 40
output : band 1 band 2 band 3




programB


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#include <iostream>
using namespace std;

int main() {
	int marks, band;

	cout << "Enter your marks: ";
	cin >> marks;

	band = 1;
if (marks > 50) 
    if (marks < 75)
	band = 2;	
else
band = 3;

	cout << "You are in band " << band << endl;

    system("PAUSE");  // for Dev C++ 
	return 0;
}


sample input : 80 60 40
output : band 3 band 2 band 1
Last edited on
MiiNiPaa (8886)
Format your code properly and everything will be clear:
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band = 1;
if (marks > 50) 
{
    if (marks < 75)
        band = 2;	
} 
else
    band = 3;

//VS

band = 1;
if (marks > 50) 
    if (marks < 75)
        band = 2;	
    else
        band = 3;
If first case else is grouped with first if and is executed when it is false (marks <= 50)
In second case it is grouped with second if and executed when it is false (marks >= 75)
Last edited on
mutexe (2372)
Because in the second case the else is 'paired' with your second if. Not the first. Your indentation is confusing you.
Lee125 (67)
Thanks MiiNiPaa and mutexe.
i understood now.

MiiNiPaa is this more proper format than before?
Thanks for telling about the format.
Last edited on
MiiNiPaa (8886)
Basic rule of indent: lines belonging to the same "level of execution" should be lined vertically. Lines of nested code blocks should be deeper.

As for style of formatting, pick whichever you like: http://en.wikipedia.org/wiki/Indent_style
I prefer K&R and would write your code as:
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#include <iostream>

int main() {
    int marks;
    std::cout << "Enter your marks: ";
    std::cin >> marks;

    int band = 1;
    if (marks > 50) {
        if (marks < 75)
            band = 2;	
    } else
        band = 3;
    std::cout << "You are in band " << band << '\n';
}


Check if you IDE provide autoindent feature (and tell it to replce tabs with spaces: do not mix tabs and spaces as indent). Most modern ones do.
Last edited on
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