| Revision as of 22:28, 5 August 2010 editRichfife (talk | contribs)Extended confirmed users7,113 edits You'd have to make a special effort to write a non-thread safe atoi(), but, yes, the reference supports the claim that it's happened at least once.← Previous edit | Revision as of 13:03, 19 August 2010 edit undo1exec1 (talk | contribs)Pending changes reviewers, Rollbackers50,085 editsm copy-editedNext edit → | ||
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| {{lowercase|title=atoi}} | {{lowercase|title=atoi}} | ||
| '''atoi''' ('''A'''SCII '''to''' '''i'''nteger) is a function in the ], which is used to convert a string into a numerical representation. | |||
| :<code>int '''atoi'''(const char *str) </code> | :<code>int '''atoi'''(const char *str) </code> | ||
Revision as of 13:03, 19 August 2010
atoi (ASCII to integer) is a function in the C programming language, which is used to convert a string into a numerical representation.
int atoi(const char *str)
The str argument is a string, represented by an array of characters, containing the characters of a signed integer number. The string must be null-terminated. When atoi encounters a string with no numerical sequence, it returns zero (0). If the string holds a valid sequence of digits that represents the number 0, it also returns a 0, making it impossible to tell from the return value alone whether the string holds a valid number or not. The newer function strtol does not have this deficiency.
Other problems of atoi are that it is not thread-safe and not async-cancel safe on some operating systems.
Variants of the atoi function, atol, atof, and atoll (the latter formerly known as atoq), are used to convert a string into a long, double, or long long type, respectively:
long atol(const char *str)double atof(const char *str)long long atoll(const char *str)(C99)
Standards conformance
The atoi, atof, and atol functions are a part of the ISO standard C library (C89), while the atoll function is added by C99.
However, because of the ambiguity in returning 0 and lack of thread-safety and async-cancel safety on some operating system, atoi is considered to be deprecated by strtol.
References
The Version 7 Unix Manual Pages © 1979 by Bell Telephone Laboratories, Incorporated.
The Version 1 Unix Manual page for atoi written by Ken Thompson (November 1971).