Converting Between Numbers and Strings
The standard library provides a variety of functions to interpret a numeral string and return a numeric value. These functions are listed in Following Table. The numeral conversion functions differ both in their target types and in the string types they interpret. The functions for char strings are declared in the header stdlib.h, and those for wide strings in wchar.h.
Conversion of numeral strings
| Conversion | Functions in stdlib.h | Functions in wchar.h |
|---|---|---|
| String to int | atoi( ) | |
| String to long | atol( ), strtol( ) | wcstol( ) |
| String to unsigned long | strtoul( ) | wcstoul( ) |
| String to long long | atoll( ), strtoll( ) | wcstoll( ) |
| String to unsigned long long | strtoull( ) | wcstoull( ) |
| String to float | strtof( ) | wcstof( ) |
| String to double | atof( ), strtod( ) | wcstod( ) |
| String to long double | strtold( ) | wcstold( ) |
Conversions between strings and numbers using format strings
| Conversion | Functions in stdio.h | Functions in wchar.h |
|---|---|---|
| String to number | sscanf( ), vsscanf( ) | swscanf( ), vswscanf( ) |
| Number to string | sprintf( ), snprintf( ), vsprintf( ), vsnprintf( ) | swprintf( ), vswprintf( ) |
