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How to reverse an integer - C/C++

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  Ángel Manuel García Carmona's Photo Submitted by Ángel Manuel García Carmona Peacock
Posted Aug 18 2011 07:00 AM
[REMEMBER:] An integer is a whole number (not a fraction) that can be positive, negative, or zero. For example, 112 and -5 are integers.

If we want to reverse an integer by C/C++, you must to use the following code block, which you can logically adapt to your app and represents a function:

int reverseint(int num_)
{
	int inv; inv = 0;

	while (num_>0)
	{
		inv = inv * 10 + (num_%10);
		num_ = num_ / 10;
	}

	return inv;
}

This code is similar on another programming languages as C#, Java and Javascript.
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2 Replies

mchammer  : Aug 23 2011 01:19 PM
So, how does this reverse a negative integer?
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  krisk1958's Photo Alternative solution by krisk1958
Posted Aug 23 2011 09:25 PM
// -52 -> -25
// 67 -> 76
int reverseint(int num_)
{
int sign;
int inv;

inv = 0;
sign = num_>0?1:-1;

num_ = num_ * sign;

while (num_>0)
{
inv = inv * 10 + (num_%10);
num_ = num_ / 10;
}

return inv * sign;
}

 
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