CTEC1335/2008F

Using C Standard Library Functions to Convert String Input
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#include <cstdlib>

int atoi( const char * s ) ;

http://www.cplusplus.com/reference/clibrary/cstdlib/atoi.html


double atof( const char * s ) ;

http://www.cplusplus.com/reference/clibrary/cstdlib/atof.html


Limitations:

Both functions return a zero if the a numeric value cannot be
converted, which makes it difficult to determine if an actual
zero value was converted.


#include <cstdio>

int sscanf( const char * s, const char * format, ... ) ;

http://www.cplusplus.com/reference/clibrary/cstdio/sscanf.html

Limitations:

Large values will either be "wrapped around" (ints) or converted
to an "infinite" value.  Small values will be converted to zero.


To convert a C++ string variable to a C-style string, use the

const char * c_str( ) const ;

method.

http://www.cplusplus.com/reference/string/string/c_str.html

For example,

string s ;

. . .

const char * cs = s.c_str( ) ;



Example programs:

atof.cpp		Demonstrate using atof( ) for double input
atoi.cpp		Demonstrate using atoi( ) for int input
sscanfdouble.cpp	Demonstrate using sscanf( ) for double input
sscanfint.cpp		Demonstrate using sscanf( ) for int input
stringUtil.cpp		String utility library, for use with parsers
stringUtil.h		String utility library header file
stripleading.cpp	Test program for stripleadingspace( ) function
striptailing.cpp	Test program for striptailingspace( ) function
parseInt.cpp		An integer parser

For the first four programs atox.cpp and sscanfxxx.cpp, compile with:

cl /EHsc ____.cpp

For the stringUtil.cpp, compile with:

cl /I. /EHsc /C stringUtil.cpp

For the last three programs (stripxxx.cpp and parseInt.cpp), compile with:

cl /I. /EHsc _____.cpp stringUtil.obj