Summerizing out:string to int,int to string

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1.

integer = atoi( my_string.c_str() );

2.

#include <iostream>
#include <sstream>//用这个类；

int main()
{
using namespace std;

string s = "1234";
stringstream ss(s); // Could of course also have done ss("1234") directly.

int i;
ss >> i;
cout << i << endl;

return 0;
}

3

.#include <boost/lexcal_cast.hpp>

// ...
int i = 42;
std::string s = boost::lexical_cast<std::string>(i);
int j = boost::lexical_cast<int>(s)

4.

#include <iostream>
#include <limits>

using namespace std;

int main ( int argc, char* argv[] )
{
int i;
cout << "enter an interger (or some random garbage): ";
cout.flush();
while ( (cin >> i).fail() )
{
// clear the error flag in the cin object
cin.clear();
// discard the erroneous user input
cin.ignore(numeric_limits<streamsize>::max(), '\n');
cout << "ooops! please try again: ";
cout.flush();
}
cout << "thank you for entering " << i << endl;
}

This technique should be applicable to other stream objects and other non-integer types.

[url]http://www.cplusplus.com/reference/iostream/ios/fail.html[/url]
[url]http://www.cplusplus.com/reference/iostream/ios/clear.html[/url]
[url]http://www.cplusplus.com/reference/iostream/istream/ignore.html[/url]
[url]http://www.cplusplus.com/reference/iostream/streamsize.html[/url]
[url]http://publib.boulder.ibm.com/infocenter/comphelp/v9v111/index.jsp?topic=/com.ibm.xlcpp9.aix.doc/standlib/header_limits.htm[/url]
5.

string IntToString(int intValue) { 
  char *myBuff; 
  string strRetVal; 

  // Create a new char array 
  myBuff = new char[100]; 

  // Set it to empty 
  memset(myBuff,'\0',100); 

  // Convert to string 
  itoa(intValue,myBuff,10); 

  // Copy the buffer into the string object 
  strRetVal = myBuff; 

  // Delete the buffer 
  delete[] myBuff; 

  return(strRetVal); 
}

6.最后一个偶认为最好

int i=4507;   // any value can be assigned
string s;
char b[MAX];  // max is the maximum no of digits in a number

sprintf(b,"%d",i);// C-style string formed without null

s+=b; //c++ string(c++ STL string) is not necessarily null terminated

标准 C I/O
sprintf
语法:

 #include <stdio.h>
  int sprintf( char *buffer, const char *format, ... );

sprintf()函数和printf()类似, 只是把输出发送到buffer(缓冲区)中.返回值是写入的字符数量.