Difference between revisions of "cpp/string/basic string/stol"
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Revision as of 07:34, 1 August 2012
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Interprets a signed integer value in the string str.
Discards any whitespace characters (as identified by calling std::isspace) until the first non-whitespace character is found, then takes as many characters as possible to form a valid base-n (where n=base) integer number representation and converts them to an integer value. The valid integer value consists of the following parts:
- (optional) plus or minus sign
- (optional) prefix (
0) indicating octal base (applies only when the base is 8 or 0) - (optional) prefix (
0xor0X) indicating hexadecimal base (applies only when the base is 16 or 0) - a sequence of digits
The set of valid values for base is {0,2,3,...,36}. The set of valid digits for base-2 integers is {0,1}, for base-3 integers is {0,1,2}, and so on. For bases larger than 10, valid digits include alphabetic characters, starting from Aa for base-11 integer, to Zz for base-36 integer. The case of the characters is ignored.
Additional numeric formats may be accepted by the currently installed C locale.
If the value of base is 0, the numeric base is auto-detected: if the prefix is 0, the base is octal, if the prefix is 0x or 0X, the base is hexadecimal, otherwise the base is decimal.
If the minus sign was part of the input sequence, the numeric value calculated from the sequence of digits is negated as if by unary minus in the result type.
The index of the first unconverted character is stored in pos. If NULL is passed as pos, it is ignored.
Contents |
Parameters
| str | - | the string to convert |
| pos | - | address of an integer to store the index of the first unconverted character |
| base | - | the number base |
Return value
The string converted to the specified signed integer type.
Exceptions
- std::invalid_argument if no conversion could be performed
- std::out_of_range if the converted value would fall out of the range of the result type.
Example
#include <iostream> #include <string> int main() { std::string test = "45"; int myint = stoi(test); std::cout << myint << '\n'; }
Output:
45
