string to int

最新推荐文章于 2023-08-10 12:45:01 发布

转载最新推荐文章于 2023-08-10 12:45:01 发布 · 536 阅读

文章标签：

#string #function #integer #object #date #system

Comment from Sys_Prog
Date: 03/08/2004 08:59PM PST
Comment

I doubt if there is some STL function for that

However u can simple use the ascii conversion

Example
Suppose I have a numeric digit in char and I want to convert it to an int, then just subtract '0' from the char and assign the result of subtraction to the int

example

char c = '2' ;
int no ;

no = c - '0' ;
cout << no ;

Similarly, You will have to do it for multiple digits using a loop and manipulating

Since u have a std::string type of object, you can use the c_str() function of std::string to get a char array format of your string

Link for std::string reference
http://www.cppreference.com/cppstring.html

HTH

Amit

Comment from Sys_Prog
Date: 03/08/2004 09:08PM PST
Comment

The foll would be the manipulation of the complete char array

int main()
{
    char str[] = "123" ;

      int no = 0 ;
      int i = 0 ;

      while ( str [ i ] != '{row.content}' ) {
            no = no * 10 ;
                no = no + ( str [ i ] - '0' ) ;
            i++ ;
      }
       cout << no ;
    system ( "PAUSE" ) ;
    return 0;
}

Just add the code for converting the string object to a char array (as I posted in the link above)

HTH

Amit

Assisted Answer from roshmon
Date: 03/08/2004 09:38PM PST
Grade: A
Assisted Answer

What about this

string a="321"
int b = atoi(a.c_str());

Rosh

Accepted Answer from Bird__
Date: 03/08/2004 10:08PM PST
Grade: A
Accepted Answer

as you want to use the stl, forget about atoi because it's not part of the stl
instead, use stringstreams

i.e.

#include <iostream>
#include <sstream>

int main( )
{
    std::string a("321");
    int b;
    std::stringstream ss(a);
    ss >> b;
    std::cout << b;
    return 0;
}

you could have also used

std::stringstream ss;
ss << a;

to input the string into the stringstream, and this can be used with any built in type (i.e. for converting ints to strings, etc) as well as objects (if set up correctly).

Comment from Bronek-K
Date: 03/13/2004 07:48AM PST
Comment

Hi Carl3003, try this:

#include <sstream>
#include <iostream>
#include <cstdio>

template <typename Source>
std::string make_string(Source s)
{
std:: ostringstream buf;
buf << s;
return buf.str();
}

int main()
{
int t1 = 123;
std::string s1 = make_string(t1);
std::cout << s1 << std::endl;
printf("%s\n", s1.c_str());

long t2 = 456;
std::string s2 = make_string(t2);
std::cout << s2 << std::endl;
printf("%s\n", s2.c_str());

double t3 = 789.01;
std::string s3 = make_string(t3);
std::cout << s3 << std::endl;
printf("%s\n", s3.c_str());
}

Comment from cool_alok
Date: 03/17/2004 01:58AM PST
Comment

hellooo mr carl
there is very simple function defined in stdlib.h
named
itoa: which convert integer to string
ultoa: which convert long to string
and viceversa
atoi for converting string to integer
also
_fcvt for float
thanks
ALok

Comment from jcac2000
Date: 05/19/2004 11:48AM PDT
Comment

c big number calculator

from : http://ssmir.ycool.com/post.297034.html