how to make negative numbers into positive - c

Question

I am having the negative floating point number as:
a = -0.340515;
to convert this into positive number I used the abs() method as:
a = abs(a);
the result is a = 0.000000;
But I need the result as 0.340515.
Can anyone tell me how to do this.

Answer 1

abs() is for integers only. For floating point, use fabs() (or one of the fabs() line with the correct precision for whatever a actually is)

Answer 2

You have to use: abs() for int fabs() for double fabsf() for float Above function will also work but you can also try something like this.
if(a<0)
{
a=-a;
}

Answer 3

Use float fabsf (float n) for float values.
Use double fabs (double n) for double values.
Use long double fabsl(long double) for long double values.
Use abs(int) for int values.

Answer 4

Well, in mathematics to convert a negative number to a positive number you just need to multiple the negative number by -1;
Then your solution could be like this:
a = a * -1;
or shorter:
a *= -1;

Answer 5

a *= (-1);
problem solved. If there is a smaller solution for a problem, then why you guys going for a complex solution. Please direct people to use the base logic also because then only the people can train their programming logic.

Answer 6

floor a;
floor b;
a = -0.340515;
so what to do?
b = 65565 +a;
a = 65565 -b;
or
if(a < 0){
a = 65565-(65565+a);}

Answer 7

#include <iostream>
using namespace std;
int makePositiveSUM(int a,int b);
int main() {
int t;
cin>>t;
while(t--){
int x,y;
cin>>x>>y;
cout<<makePositiveSUM(x,y)<<endl;
}
return 0;
}
int makePositiveSUM(int a,int b){
if(a>b){
return a-b;
}
else {
return b-a;
}
}
enter code here
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enter code here

Answer 8

this is the only way i can think of doing it.
//positive to minus
int a = 5; // starting with 5 to become -5
int b = int a * 2; // b = 10
int c = a - b; // c = - 5;
std::cout << c << endl;
//outputs - 5
//minus to positive
int a = -5; starting with -5 to become 5
int b = a * 2;
// b = -10
int c = a + b
// c = 5
std::cout << c << endl;
//outputs 5
Function examples
int b = 0;
int c = 0;
int positiveToNegative (int a) {
int b = a * 2;
int c = a - b;
return c;
}
int negativeToPositive (int a) {
int b = a * 2;
int c = a + b;
return c;
}

Answer 9

Why do you want to use strange hard commands, when you can use:
if(a < 0)
a -= 2a;
The if statement obviously only applies when you aren't sure if the number will be positive or negative.
Otherwise you'll have to use this code:
a = abs(a) // a is an integer
a = fabs(a) // a is declared as a double
a = fabsf(a) // a is declared as a float (C++ 11 is able to use fabs(a) for floats instead of fabs)
To activate C++ 11 (if you are using Code::Blocks, you have to:
Open up Code::Blocks (recommended version: 13.12).
Go to Settings -> Compiler.
Make sure that the compiler you use is GNU GCC Compiler.
Click Compiler Settings, and inside the tab opened click Compiler Flags
Scroll down until you find: Have g++ follow the C++ 11 ISO C++ language standard [-std=c++11]. Check that and then hit OK button.
Restart Code::Blocks and then you are good to go!
After following these steps, you should be able to use fabs(a) for floats instead of fabsf(a), which was used only for C99 or less! (Even C++ 98 could allow you to use fabs instead of fabsf :P)