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std::atoi, std::atol, std::atoll

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< cpp‎ | string‎ | byte

 
 
Strings Bibliothek
Null-terminierte Strings
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Null-terminated strings
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Byte-Strings
Multibyte-Strings
Wide Strings
Classes
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Classes
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basic_string
char_traits
 
Null-terminierte Byte-Strings
Funktionen
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Functions
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Character Manipulation
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Character manipulation
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Umwandlungen in numerische Formate
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Conversions to numeric formats
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atof
atoi
atol
atoll
strtol
strtoll
String-Manipulation
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String manipulation
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strcpy
strncpy
strcat
strncat
strxfrm
String Prüfung
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String examination
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Speicher Manipulation
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Memory manipulation
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memchr
memcmp
memset
memcpy
memmove
Verschiedenes
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Miscellaneous
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strerror
 
Defined in header <cstdlib>
int       atoi( const char *str );
long      atol( const char *str )
long long atoll( const char *str );
(seit C++11)
Interpretiert den Byte String str als Integer-Wert.
Original:
Interprets an integer value in a byte string pointed to by str.
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Die Funktion verwirft alle Leerzeichen bis zum ersten Nicht-Whitespace-Zeichen. Dann werden solange Zeichen gelesen, solange sie eine gültige ganze Zahl darstellen. Die gelesenen Zeichen werden anschließend in einen Integer-Wert umgewandelt. Der gültige Integer-Wert besteht aus den folgenden Teilen:
Original:
Function discards any whitespace characters until first non-whitespace character is found. Then it takes as many characters as possible to form a valid integer number representation and converts them to integer value. The valid integer value consists of the following parts:
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  • (optional) Plus-oder Minuszeichen
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    (optional) plus or minus sign
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  • Ziffern
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    numeric digits
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Inhaltsverzeichnis

[Bearbeiten] Parameter

str -
Zeiger auf den umzuwandelnden null-terminierten Byte-String
Original:
pointer to the null-terminated byte string to be interpreted
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[Bearbeiten] Rückgabewert

Im Erfolgsfall der dem Inhalt von str entsprechende Integer-Wert. Falls der konvertierte Wert außerhalb des Wertebereichs des entsprechenden Rückgabetyps liegt, ist der Rückgabewert undefiniert. Falls keine Umwandlung möglich ist, wird 0 zurückgegeben.
Original:
Integer value corresponding to the contents of str on success. If the converted value falls out of range of corresponding return type, the return value is undefined. If no conversion can be performed, 0 is returned.
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[Bearbeiten] Beispiel

#include <iostream>
#include <cstdlib>
 
int main()
{
    const char *str1 = "42";
    const char *str2 = "3.14159";
    const char *str3 = "31337 with words";
    const char *str4 = "words and 2";
 
    int num1 = std::atoi(str1);
    int num2 = std::atoi(str2);
    int num3 = std::atoi(str3);
    int num4 = std::atoi(str4);
 
    std::cout << "std::atoi(\"" << str1 << "\") is " << num1 << '\n';
    std::cout << "std::atoi(\"" << str2 << "\") is " << num2 << '\n';
    std::cout << "std::atoi(\"" << str3 << "\") is " << num3 << '\n';
    std::cout << "std::atoi(\"" << str4 << "\") is " << num4 << '\n';
}

Output:

std::atoi("42") is 42
std::atoi("3.14159") is 3
std::atoi("31337 with words") is 31337
std::atoi("words and 2") is 0

[Bearbeiten] Siehe auch

(C++11)
(C++11)
(C++11)
wandelt einen String in eine Ganzzahl
Original:
converts a string to an signed integer
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(Funktion) [edit]
wandelt ein Byte-String in einen ganzzahligen Wert
Original:
converts a byte string to an integer value
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(Funktion) [edit]
wandelt ein Byte-String in einen vorzeichenlosen Integer-Wert
Original:
converts a byte string to an unsigned integer value
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(Funktion) [edit]
C documentation for atoi, atol, atoll