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Difference between revisions of "cpp/string/byte/strtoimax"

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< cpp‎ | string‎ | byte
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{{cpp/title| strtoimax| strtoumax}}
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{{cpp/title|strtoimax|strtoumax}}
 
{{cpp/string/byte/navbar}}
 
{{cpp/string/byte/navbar}}
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{{ddcl list begin}}
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{{dcl begin}}
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{{ddcl list header | cinttypes}}
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{{dcl header|cinttypes}}
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{{ddcl list item |  
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{{dcl|since=c++11|num=1|
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std::intmax_t strtoimax(const char* nptr, char** endptr, int base);
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std::intmax_t strtoimax( const char* nptr, char** endptr, int base );
 
}}
 
}}
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{{ddcl list item | notes={{mark since c++11}} |
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{{dcl|since=c++11|num=2|
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std::uintmax_t strtoumax(const char* nptr, char** endptr, int base);
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std::uintmax_t strtoumax( const char* nptr, char** endptr, int base );
 
}}
 
}}
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{{ddcl list end}}
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{{dcl end}}
  
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Interprets an integer value in a byte string pointed to by {{tt|nptr}}.
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Interprets an integer value in a byte string pointed to by {{c|nptr}}.
  
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{{cpp/string/cvt str2int base | base=base}}
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{{cpp/string/cvt str2int base|base=base}}
  
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The functions sets the pointer pointed to by {{tt|endptr}} to point to the character past the last character interpreted. If {{tt|endptr}} is {{c|NULL}}, it is ignored.
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The functions sets the pointer pointed to by {{c|endptr}} to point to the character past the last character interpreted. If {{c|endptr}} is a null pointer, it is ignored.
  
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If the {{tt|nptr}} is empty or does not have the expected form, no conversion is performed, and (if {{tt|enptr}} is not {{c|NULL}}) the value of {{tt|nptr}} is stored in the object pointed to by {{tt|endptr}}.
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If the {{c|nptr}} is empty or does not have the expected form, no conversion is performed, and (if {{c|enptr}} is not a null pointer) the value of {{c|nptr}} is stored in the object pointed to by {{c|endptr}}.
  
 
===Parameters===
 
===Parameters===
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{{param list begin}}
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{{par begin}}
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{{param list item | nptr | pointer to the null-terminated byte string to be interpreted}}
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{{par|nptr|pointer to the null-terminated byte string to be interpreted}}
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{{param list item | endptr | pointer to a pointer to character.}}
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{{par|endptr|pointer to a pointer to character.}}
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{{param list item | base | ''base'' of the interpreted integer value}}
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{{par|base|''base'' of the interpreted integer value}}
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{{param list end}}
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{{par end}}
  
 
===Return value===
 
===Return value===
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* If successful, an integer value corresponding to the contents of {{c|str}} is returned.
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* If successful, an integer value corresponding to the contents of {{tt|str}} is returned.
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* If the converted value falls out of range of corresponding return type, a range error occurs (setting {{lc|errno}} to {{lc|ERANGE}}) and {{lc|INTMAX_MAX}}, {{lc|INTMAX_MIN}}, {{lc|UINTMAX_MAX}} or {{c|0}} is returned, as appropriate.
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* If the converted value falls out of range of corresponding return type, a range error occurs (setting [[cpp/error/errno|{{c|errno}}]] to {{c|ERANGE}}) and {{c|INTMAX_MAX}}, {{c|INTMAX_MIN}}, {{c|UINTMAX_MAX}} or {{c|UINTMAX_MIN}} is returned.  
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* If no conversion can be performed, {{c|0}} is returned.
 
* If no conversion can be performed, {{c|0}} is returned.
  
 
===Example===
 
===Example===
 
{{example
 
{{example
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|
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|code=
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| code=
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#include <iostream>
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#include <cinttypes>
 
#include <cinttypes>
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#include <iostream>
 +
#include <string>
  
 
int main()
 
int main()
Line 47: Line 46:
 
     char* nptr;
 
     char* nptr;
 
     val = std::strtoimax(str.c_str(), &nptr, 30);
 
     val = std::strtoimax(str.c_str(), &nptr, 30);
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     if(nptr != &str[0] + str.size())
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     if (nptr != &str[0] + str.size())
 
         std::cout << str << " in base 30 is invalid."
 
         std::cout << str << " in base 30 is invalid."
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                   << " The first invalid digit is " << *nptr << '\n';
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                   << " The first invalid digit is '" << *nptr << "'\n";
 
}
 
}
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| output=
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|output=
 
helloworld in base 36 is 1767707668033969 in base 10
 
helloworld in base 36 is 1767707668033969 in base 10
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helloworld in base 30 is invalid. The first invalid digit is w
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helloworld in base 30 is invalid. The first invalid digit is 'w'
 
}}
 
}}
  
 
===See also===
 
===See also===
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{{dcl list begin}}
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{{dsc begin}}
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{{dcl list template | cpp/string/byte/dcl list strtol}}
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{{dsc inc|cpp/string/basic_string/dsc stol}}
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{{dcl list template | cpp/string/byte/dcl list strtoul}}
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{{dsc inc|cpp/string/basic_string/dsc stoul}}
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{{dcl list see c | c/string/byte/strtoimax | strtoimax | strtoumax}}
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{{dsc inc|cpp/string/byte/dsc strtol}}
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{{dcl list end}}
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{{dsc inc|cpp/string/byte/dsc strtoul}}
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{{dsc inc|cpp/string/wide/dsc wcstoimax}}
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{{dsc inc|cpp/string/byte/dsc strtof}}
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{{dsc inc|cpp/utility/dsc from_chars}}
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{{dsc inc|cpp/string/byte/dsc atoi}}
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{{dsc see c|c/string/byte/strtoimax|strtoimax|strtoumax}}
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{{dsc end}}
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 +
{{langlinks|de|es|fr|it|ja|pt|ru|zh}}

Latest revision as of 08:44, 6 June 2023

 
C++
 
Strings library
 
Null-terminated byte strings
Functions
Character manipulation
Conversions to numeric formats
(C++11)
(C++11)(C++11)
strtoimaxstrtouimax
(C++11)(C++11)
String manipulation
String examination
Memory manipulation
Miscellaneous
 
Defined in header <cinttypes>
std::intmax_t strtoimax( const char* nptr, char** endptr, int base );
 (1) (since C++11)
std::uintmax_t strtoumax( const char* nptr, char** endptr, int base );
 (2) (since C++11)

Interprets an integer value in a byte string pointed to by nptr.

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 (0x or 0X) 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 functions sets the pointer pointed to by endptr to point to the character past the last character interpreted. If endptr is a null pointer, it is ignored.

If the nptr is empty or does not have the expected form, no conversion is performed, and (if enptr is not a null pointer) the value of nptr is stored in the object pointed to by endptr.

Contents

[edit] Parameters

nptr - pointer to the null-terminated byte string to be interpreted
endptr - pointer to a pointer to character.
base - base of the interpreted integer value

[edit] Return value

  • If successful, an integer value corresponding to the contents of str is returned.
  • If the converted value falls out of range of corresponding return type, a range error occurs (setting errno to ERANGE) and INTMAX_MAX, INTMAX_MIN, UINTMAX_MAX or ​0​ is returned, as appropriate.
  • If no conversion can be performed, ​0​ is returned.

[edit] Example

Run this code
#include <cinttypes>
#include <iostream>
#include <string>
 
int main()
{
    std::string str = "helloworld";
    std::intmax_t val = std::strtoimax(str.c_str(), nullptr, 36);
    std::cout << str << " in base 36 is " << val << " in base 10\n";
 
    char* nptr;
    val = std::strtoimax(str.c_str(), &nptr, 30);
    if (nptr != &str[0] + str.size())
        std::cout << str << " in base 30 is invalid."
                  << " The first invalid digit is '" << *nptr << "'\n";
}

Output: 

helloworld in base 36 is 1767707668033969 in base 10
helloworld in base 30 is invalid. The first invalid digit is 'w'

[edit] See also

(C++11)(C++11)(C++11)
 converts a string to a signed integer
(function) [edit]
(C++11)(C++11)
 converts a string to an unsigned integer
(function) [edit]
(C++11)
 converts a byte string to an integer value
(function) [edit]
(C++11)
 converts a byte string to an unsigned integer value
(function) [edit]
(C++11)(C++11)
 converts a wide string to std::intmax_t or std::uintmax_t
(function) [edit]
converts a byte string to a floating-point value
(function) [edit]
(C++17)
 converts a character sequence to an integer or floating-point value
(function) [edit]
(C++11)
 converts a byte string to an integer value
(function) [edit]
C documentation for strtoimax, strtoumax
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