ambiguity square root

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C++ compiler error: ambiguous call to overloaded function

just copied some code from a pdf into both C++builder XE2 and visual studio express 2012. both both compilers give error codes about ambiquity. I just started so i don't really know what to do. Maybe my textbook(pdf) is old and obsolete now? it's called "Learn c++ in 14 days". Well anyways here is the copied code.

#include <iostream.h>
#include <conio.h>
#include <math.h>
#include <stdio.h>
#pragma hdrstop
void getSqrRoot(char* buff, int x);
int main(int argc, char** argv)
{
int x;
char buff[30];
cout << “Enter a number: “;
cin >> x;
getSqrRoot(buff, x);
cout << buff;
getch();
}
void getSqrRoot(char* buff, int x)
{
sprintf(buff, “The sqaure root is: %f”, sqrt(x));
}

the errorcode i got in c++builder is:

[BCC32 Error] SquareRoot.cpp(19): E2015 Ambiguity between 'std::sqrt(float) at c:\program files (x86)\embarcadero\rad studio\9.0\include\windows\crtl\math.h:266' and 'std::sqrt(long double) at c:\program files (x86)\embarcadero\rad studio\9.0\include\windows\crtl\math.h:302' Full parser context SquareRoot.cpp(18): parsing: void getSqrRoot(char *,int)

On a side note, the quotation marks in my pdf manual are different characters than the normal " which i type. these “ are also not compatible with the compiler. maybe anybody knows a fix for this as well? thanks in advance.

There is no fix you're supposed to use "..." and not whatever else is in your pdf. You could just cast your int to a double: `sqrt(static_cast(x))` — Borgleader, Dec 14 '12 at 06:59
Avoid any *C++ in X period of time* book unless said period of time is "two lifetimes". There is a list of good books here: http://stackoverflow.com/questions/388242/the-definitive-c-book-guide-and-list — R. Martinho Fernandes, Dec 14 '12 at 07:00
I'm surprised the supplied code doesn't give more errors, e.g. for the UNICODE quotation marks `“` around the strings. — Some programmer dude, Dec 14 '12 at 08:17
Well, a book that promises you to learn C++ in 14 days is likely to propagate the use of `` in C++ code or, even better, mix things like `cin` (which misses a `std::` qualification by the way) with `getch`. You should just be thankful you didn't buy this in printed form. — Christian Rau, Dec 14 '12 at 08:44

score 3 · Accepted Answer · answered Dec 14 '12 at 07:50

Change your code like that:

void getSqrRoot(char* buff, int x)
{
 sprintf(buff, “The sqaure root is: %f”, sqrt((float)x));
}

Because square root is overloaded function compiler has no opportunity to implicit conversion from int x value to float or double value, you need to do it directly.

Compiler: see sqrt(int) -> what to choose? sqrt(float)/sqrt(double) ?
Compiler: see sqrt((float)int) -> sqrt(float), ok!
Compeler: see sqrt((double)int) -> sqrt(double), ok!

thanks for the answers, this compiler interpretation text is really helpful. — Electric Vibes, Dec 14 '12 at 13:23

score 1 · Answer 2 · answered Dec 14 '12 at 07:02

Change your getSqrRoot Function to the below

void getSqrRoot(char* buff, float x)
{

And similarly fix the declaration in the first line.

This is happening because std::sqrt which is the function you are using to get the square root, can take either a float or a double but you have given it an int which leads to the confusion since the compiler now has no idea which function to call.

ambiguity square root

2 Answers2