- Atoi
The atoi (ASCII to Integer) function in the
C programming language is used to convert a string into a numerical representation.:
int atoi (const char *string)Where
stringis the string, represented by an array of characters. When atoi encounters a string with no numerical sequence, it returns a 0 (zero). Also, if the string holds a valid sequence of digits that represents the number 0, it would also return a 0, making it impossible to tell from the return value alone whether the string held a valid number or not. The newer functionstrtol does not have this deficiency.Variants of the atoi function, atol, atof, and atoll (the latter formerly known as atoq), are used to convert a string into a long, float, or long long integer, respectively:
:
long atol (const char *string):double atof(const char *string):long long atoll (const char *string)(C99 )tandards 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 .ee also
*
atof
*itoa
*strtol
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