Interprets a floating-point value in a byte string pointed to bystr.

Function discards any whitespace characters (as determined byisspace) until first non-whitespace character is found. Then it takes as many characters as possible to form a valid floating-point representation and converts them to a floating-point value. The valid floating-point value can be one of the following:

• decimal floating-point expression. It consists of the following parts:

• (optional) plus or minus sign
• nonempty sequence of decimal digits optionally containing decimal-point character (as determined by the current Clocale) (defines significand)
• (optional)e orE followed with optional minus or plus sign and nonempty sequence of decimal digits (defines exponent to base10)

• any other expression that may be accepted by the currently installed Clocale.

[edit]Parameters

[edit]Return value

double value corresponding to the contents ofstr on success. If the converted value falls out of range of the return type, the return value is undefined. If no conversion can be performed,0.0 is returned.

[edit]Notes

The name stands for “ASCII to float”.

[edit]Example

#include <stdio.h>#include <stdlib.h> int main(void){printf("%g\n", atof("  -0.0000000123junk"));printf("%g\n", atof("0.012"));printf("%g\n", atof("15e16"));printf("%g\n", atof("-0x1afp-2"));printf("%g\n", atof("inF"));printf("%g\n", atof("Nan"));printf("%g\n", atof("1.0e+309"));// UB: out of range of doubleprintf("%g\n", atof("0.0"));printf("%g\n", atof("junk"));// no conversion can be performed}

-1.23e-080.0121.5e+17-107.75infnaninf00

[edit]References

[edit]See also

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