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how to convert a string value to float or double?
i use atoi function but giving me integer value
sample code:
sample output:Code:int main()
{
string a = "5.1234";
float b;
b = atoi(a.c_str());
cout<<b;
return 0;
}
5
but i want to get is 5.1234
got any solution?
You can also use atof, which is the same as atoi but wprks with floating point values instead. BTW, generally you should use double instead of float unless you have a good reason.
atof is been subsumed by strtod but have been retained because they are used extensively in existing code. They are less reliable, but may be faster if the argument is known to be in a valid range.
Use strtod instead because they offer more control over the conversion process, and because they are required not to produce unexpected results on overflow during conversion.
Those do the reverse.Quote:
Originally Posted by dwks
The first link uses C++ stringstreams. it is simple to reverse that process.Quote:
Those do the reverse.
Code:int StringToInt(string s)
{
stringstream myStream(s);
int num;
myStream >> num;
if (!myStream)
{
cout << "ERROR: Not a number" << endl;
return 0;
}
else
return num;
}
The OP wanted a float or double, but I agree with your point. Here's another version:Quote:
Originally Posted by Bench82
[39.2] How do I convert a std::string to a number?