Data Conversion These routines convert data from one form to another. Generally these routines execute faster than conversions you might write. Each routine that begins with a to prefix is implemented as a function and as a macro. See Choosing Between Functions and Macros for information about choosing an implementation. Data-Conversion Routines Routine

Use

abs

Find absolute value of integer

atof

Convert string to float

atoi, _atoi64

Convert string to int

atol

Convert string to long

_ecvt

Convert double to string of specified length

_fcvt

Convert double to string with specified number of digits following decimal point

_gcvt

Convert double number to string; store string in buffer

_itoa, _i64toa, _itow, _i64tow

Convert int to string

labs

Find absolute value of long integer

_ltoa, _ltow

Convert long to string

_mbbtombc

Convert 1-byte multibyte character to corresponding 2-byte multibyte character

_mbcjistojms

Convert Japan Industry Standard (JIS) character to Japan Microsoft (JMS) character

_mbcjmstojis

Convert JMS character to JIS character

_mbctohira

Convert multibyte character to 1-byte hiragana code

_mbctokata

Convert multibyte character to 1-byte katakana code

_mbctombb

Convert 2-byte multibyte character to corresponding 1-byte multibyte character

mbstowcs

Convert sequence of multibyte characters to corresponding sequence of wide characters

mbtowc

Convert multibyte character to corresponding wide character

strtod, wcstod

Convert string to double

strtol, wcstol

Convert string to long integer

strtoul, wcstoul

Convert string to unsigned long integer

strxfrm, wcsxfrm

Transform string into collated form based on locale-specific information

__toascii

Convert character to ASCII code

tolower, towlower, _mbctolower

Test character and convert to lowercase if currently uppercase

_tolower

Convert character to lowercase unconditionally

toupper, towupper, _mbctoupper

Test character and convert to uppercase if currently lowercase

_toupper

Convert character to uppercase unconditionally

_ultoa, _ultow

Convert unsigned long to string

wcstombs

Convert sequence of wide characters to corresponding sequence of multibyte characters

wctomb

Convert wide character to corresponding multibyte character

_wtoi

Convert wide-character string to int

_wtol

Convert wide-character string to long

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atof, atoi, _atoi64, atol Convert strings to double (atof), integer (atoi, _atoi64), or long (atol). double atof( const char *string ); int atoi( const char *string ); __int64 _atoi64( const char *string ); long atol( const char *string ); Routine

Required Header

Compatibility

atof

and ANSI, Win 95, Win NT

atoi



ANSI, Win 95, Win NT

_atoi64



Win 95, Win NT

atol



ANSI, Win 95, Win NT

For additional compatibility information, see Compatibility in the Introduction. Libraries LIBC.LIB

Single thread static library, retail version

LIBCMT.LIB

Multithread static library, retail version

MSVCRT.LIB Import library for MSVCRT.DLL, retail version Return Value Each function returns the double, int, __int64 or long value produced by interpreting the input characters as a number. The return value is 0 (for atoi and _atoi64), 0L (for atol), or 0.0 (for atof) if the input cannot be converted to a value of that type. The return value is undefined in case of overflow. Parameter string String to be converted Remarks These functions convert a character string to a double-precision floating-point value (atof), an integer value (atoi and _atoi64), or a long integer value (atol). The input string is a sequence of characters that can be interpreted as a numerical value of the specified type. The output value is affected by the setting of the LC_NUMERIC category in the current

locale. For more information on the LC_NUMERIC category, see setlocale. The longest string size that atof can handle is 100 characters. The function stops reading the input string at the first character that it cannot recognize as part of a number. This character may be the null character ('\0') terminating the string. The string argument to atof has the following form: [whitespace] [sign] [digits] [.digits] [ {d | D | e | E }[sign]digits] A whitespace consists of space and/or tab characters, which are ignored; sign is either plus (+) or minus ( – ); and digits are one or more decimal digits. If no digits appear before the decimal point, at least one must appear after the decimal point. The decimal digits may be followed by an exponent, which consists of an introductory letter ( d, D, e, or E) and an optionally signed decimal integer. atoi, _atoi64, and atol do not recognize decimal points or exponents. The string argument for these functions has the form: [whitespace] [sign]digits where whitespace, sign, and digits are exactly as described above for atof. Generic-Text Routine Mappings TCHAR.H Routine

_UNICODE & _MBCS Not Defined

_MBCS Defined

_UNICODE Defined

_ttoi

atoi

atoi

_wtoi

_ttol

atol

atol

_wtol

Example /* ATOF.C: This program shows how numbers stored * as strings can be converted to numeric values * using the atof, atoi, and atol functions. */ #include #include void main( void ) { char *s; double x; int i; long l; s = " -2309.12E-15"; x = atof( s );

/* Test of atof */

printf( "atof test: ASCII string: %s\tfloat: %e\n", s, x ); s = "7.8912654773d210"; /* Test of atof */ x = atof( s ); printf( "atof test: ASCII string: %s\tfloat: %e\n", s, x ); s = " -9885 pigs";

/* Test of atoi */

i = atoi( s ); printf( "atoi test: ASCII string: %s\t\tinteger: %d\n", s, i ); s = "98854 dollars";

/* Test of atol */

l = atol( s ); printf( "atol test: ASCII string: %s\t\tlong: %ld\n", s, l ); }

Output atof test: ASCII string: -2309.12E-15 float: -2.309120e-012 atof test: ASCII string: 7.8912654773d210 float: 7.891265e+210 atoi test: ASCII string: -9885 pigs atol test: ASCII string: 98854 dollars

integer: -9885 long: 98854

Data Conversion Routines | Floating-Point Support Routines | Locale Routines See Also _ecvt, _fcvt, _gcvt, setlocale, strtod, wcstol, strtoul Send feedback to MSDN. Look here for MSDN Online resources.

strchr, wcschr, _mbschr Find a character in a string. char *strchr( const char *string, int c ); wchar_t *wcschr( const wchar_t *string, wint_t c ); unsigned char *_mbschr( const unsigned char *string, unsigned int c ); Routine

Required Header

Compatibility

strchr



ANSI, Win 95, Win NT

wcschr

or ANSI, Win 95, Win NT

_mbschr



Win 95, Win NT

For additional compatibility information, see Compatibility in the Introduction. Libraries LIBC.LIB

Single thread static library, retail version

LIBCMT.LIB

Multithread static library, retail version

MSVCRT.LIB Import library for MSVCRT.DLL, retail version Return Value Each of these functions returns a pointer to the first occurrence of c in string, or NULL if c is not found. Parameters string Null-terminated source string c Character to be located Remarks The strchr function finds the first occurrence of c in string, or it returns NULL if c is not found. The null-terminating character is included in the search. wcschr and _mbschr are wide-character and multibyte-character versions of strchr. The arguments and return value of wcschr are wide-character strings; those of _mbschr are multibyte-character strings. _mbschr recognizes multibyte-character sequences according

to the multibyte code page currently in use. These three functions behave identically otherwise. Generic-Text Routine Mappings TCHAR.H Routine

_UNICODE & _MBCS Not Defined

_MBCS Defined

_UNICODE Defined

_tcschr

strchr

_mbschr

wcschr

Example /* STRCHR.C: This program illustrates searching for a character * with strchr (search forward) or strrchr (search backward). */ #include #include int ch = 'r'; char string[] = "The quick brown dog jumps over the lazy fox"; char fmt1[] = "

1

2

3

4

5";

char fmt2[] = "12345678901234567890123456789012345678901234567890"; void main( void ) { char *pdest; int result; printf( "String to be searched: \n\t\t%s\n", string ); printf( "\t\t%s\n\t\t%s\n\n", fmt1, fmt2 ); printf( "Search char:\t%c\n", ch ); /* Search forward. */ pdest = strchr( string, ch ); result = pdest - string + 1; if( pdest != NULL ) printf( "Result:\tfirst %c found at position %d\n\n", ch, result ); else printf( "Result:\t%c not found\n" );

/* Search backward. */ pdest = strrchr( string, ch ); result = pdest - string + 1; if( pdest != NULL ) printf( "Result:\tlast %c found at position %d\n\n", ch, result ); else printf( "Result:\t%c not found\n" ); }

Output String to be searched: The quick brown dog jumps over the lazy fox 1

2

3

4

5

12345678901234567890123456789012345678901234567890 Search char: r Result: first r found at position 12 Result: last r found at position 30

String Manipulation Routines See Also strcspn, strncat, strncmp, strncpy, _strnicmp, strpbrk, strrchr, strstr Send feedback to MSDN. Look here for MSDN Online resources.