Convert a double to fixed decimal point in C++

c++ decimal fixed-point
tree-hacker picture tree-hacker · Oct 2, 2010 · Viewed 7.7k times · Source

I have a double variable in C++ and want to print it out to the screen as a fixed decimal point number.

Basically I want to know how to write a function that takes a double and a number of decimal places and prints out the number to that number of decimal places, zero padding if necessary.

For example:

convert(1.235, 2)

would print out

1.24

and

 convert(1, 3)

would print out

1.000

so the function works as

convert(number as double, number of decimal places)

and simply prints out the required value to standard output (cout).

Does anyone know how to do this?

Thanks in advance.

Answer

tc. picture tc. · Oct 2, 2010

Assuming I'm remembering my format strings correctly, 

printf("%.*f", (int)precision, (double)number);

Related questions

C++ - Decimal to binary converting

I wrote a 'simple' (it took me 30 minutes) program that converts decimal number to binary. I am SURE that there's a lot simpler way so can you show me? Here's the code: #include <iostream> #include <stdlib.h&…

Read More
Integer to hex string in C++

How do I convert an integer to a hex string in C++? I can find some ways to do it, but they mostly seem targeted towards C. It doesn't seem there's a native way to do it in C++. It …

Read More
Two decimal places using printf( )

I'm trying to write a number to two decimal places using printf() as follows: #include <cstdio> int main() { printf("When this number: %d is assigned to 2 dp, it will be: 2%f ", 94.9456, 94.9456); return 0; } When I run the program, I …

Read More