How can I convert a standard string to an integer?
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BTW, regarding the 'std::string' issue - all you have to do is calling the 'c_str()' member of that class before passing it to any of these functions, e.g.
std::string str = "1234";
int i;
i = atoi(str.c_str());
char* pc;
i = (int) strtol(str.c_str(), &pc, 10);
if ( NULL != *pc) {
// conversion error, probably incorrect numerical format
}
You are in the wrong place, suresh, I think you want http:/Programming/Programm
Though, &H0 looks like Visual Basic .NET - see http:/Programming/Programm
Business Accounts
Answer for Membership
by: jkrPosted on 2004-10-07 at 11:18:18ID: 12251838
There are several methods, the easiest being 'atoi()' the most flexible IMHO (in terms of error checking) being 'strtol()':
/* ATOF.C: This program shows how numbers stored
* as strings can be converted to numeric values
* using the atof, atoi, and atol functions.
*/
#include <stdlib.h>
#include <stdio.h>
void main( void )
{
char *s; double x; int i; long l;
s = " -2309.12E-15"; /* Test of atof */
x = atof( s );
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 integer: -9885
atol test: ASCII string: 98854 dollars long: 98854
/* STRTOD.C: This program uses strtod to convert a
* string to a double-precision value; strtol to
* convert a string to long integer values; and strtoul
* to convert a string to unsigned long-integer values.
*/
#include <stdlib.h>
#include <stdio.h>
void main( void )
{
char *string, *stopstring;
double x;
long l;
int base;
unsigned long ul;
string = "3.1415926This stopped it";
x = strtod( string, &stopstring );
printf( "string = %s\n", string );
printf(" strtod = %f\n", x );
printf(" Stopped scan at: %s\n\n", stopstring );
string = "-10110134932This stopped it";
l = strtol( string, &stopstring, 10 );
printf( "string = %s", string );
printf(" strtol = %ld", l );
printf(" Stopped scan at: %s", stopstring );
string = "10110134932";
printf( "string = %s\n", string );
/* Convert string using base 2, 4, and 8: */
for( base = 2; base <= 8; base *= 2 )
{
/* Convert the string: */
ul = strtoul( string, &stopstring, base );
printf( " strtol = %ld (base %d)\n", ul, base );
printf( " Stopped scan at: %s\n", stopstring );
}
}
Output
string = 3.1415926This stopped it
strtod = 3.141593
Stopped scan at: This stopped it
string = -10110134932This stopped it strtol = -2147483647 Stopped scan at: This stopped itstring = 10110134932
strtol = 45 (base 2)
Stopped scan at: 34932
strtol = 4423 (base 4)
Stopped scan at: 4932
strtol = 2134108 (base 8)
Stopped scan at: 932