std::strtof, std::strtod, std::strtold
From Cppreference
C++ Standard Library |
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Strings library |
Narrow null-terminated strings |
Defined in header <cstdlib>
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float strtof( const char *str, char **str_end );
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(C++11 feature) | |
double strtod( const char *str, char **str_end );
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long double strtold( const char *str, char **str_end );
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(C++11 feature) | |
Interprets a floating point value in a character string pointed to by str.
Function discards any whitespace characters 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 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 a decimal point character (defines significand)
- (optional) e or E followed with optional minus or plus sign and nonempty sequence of decimal digits (defines exponent)
- binary floating point expression. It consists of the following parts:
- (optional) plus or minus sign
- 0x or 0X
- nonempty sequence of hexadecimal digits optionally containing a decimal point character (defines significand)
- (optional) p or P followed with optional minus or plus sign and nonempty sequence of hexadecimal digits (defines exponent)
- infinity expression. It consists of the following parts:
- (optional) plus or minus sign
- INF or INFINITY ignoring case
- not-a-number expression. It consists of the following parts:
- (optional) plus or minus sign
- NAN or NAN(char_sequence) ignoring case of the NAN part. char_sequence can only contain alphanumeric characters. The result is a quiet NaN floating point value.
The functions sets the pointer pointed to by str_end to point to the character past the last character interpreted. If str_end is NULL, it is ignored.
Contents |
[edit] Parameters
str | - | pointer to the null-terminated character string to be interpreted |
str_end | - | pointer to a pointer to character. |
[edit] Return value
floating point value corresponding to the contents of str on success. If the converted value falls out of range of corresponding return type, range error occurs and HUGE_VAL, HUGE_VALF or HUGE_VALL is returned. If no conversion can be performed, 0 is returned.
This section is incomplete Reason: fix links to limits |
[edit] Example
This section is incomplete |
[edit] See also
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converts a character string to a floating point value (function) |