Passing float to a function in C appears to change precision-CodePudding

This is a very noob question, but I am curious to know the reason behind this: -If I debug the following C code:

void floatreturn(float i){
      //nothing
}

int main(){
    float a = 23.976;
    floatreturn(a);
    return 0;
}

Monitoring the passed value of a, it appears to be 23.9759998 when entering floatreturn. As a result, any processing of the value in the function would require to manually tweak the precision. Is there a reason for this, and any way to avoid it?

CodePudding user response：

The issue happened before floatreturn(a);.
It happened as float a = 23.976;
floatreturn(a); is irrelevant.

There are about 2^32 different values that float can encode exactly. 23.976 is not one of them. The nearest encodable float is about 23.9759998...

To avoid, use values that can exactly encode as a float or tolerate being close - about 1 part in 2²⁴