C++ 中 int、 char、 char、 const char、 string之间的转换

雨点打透心脏的1/2处 2022-08-21 05:37 262阅读 0赞

1. char\* to string

## string s(char \*);   注：在不是初始化的地方最好用assign().   ！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！   2. string to const char\*   string a="strte";   const char\* r=a.c\_str();   注意是const的。还要转到char\*：   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~   2.2. const char\* to char\*   const char\* r="123";   char   \*p1   =   new   char\[strlen(r)+1\];   strcpy(p1,r);   附：[http://hi.baidu.com/cfans/blog/item/06970ef4b671f366dcc4745d.html][http_hi.baidu.com_cfans_blog_item_06970ef4b671f366dcc4745d.html]   这个页面是具体讲述区别的。   ·············································································································   3. cstring to string   vs2005 Unicode下：   CStringW   str(L"test");     CStringA   stra(str.GetBuffer(0));     str.ReleaseBuffer();         std::string   strs   (stra.GetBuffer(0));     stra.ReleaseBuffer(); ##

非Unicode下：  
CString cs("test");  
std::string str=cs.getBuffer(0);  
cs.ReleaseBuffer();

注：GetBuffer()后一定要ReleaseBuffer(),否则就没有释放缓冲区所占的空间.  
\++++++++++++++++++++++++++++++++++++++++++++++++++++

4. double ,int to string  
\#include <sstream>  
using namespace std;

stringstream ss;  
string result;  
long n=11111;  
stream << n; //从long型数据输入  
stream >>result; //转换为 string

===================================================

5.char\* to int, double ,long

char \*s; double x; int i; long l;

s = " -2309.12E-15";  
x = atof( s );  
printf( "atof test: ASCII string: %s\\tfloat: %e\\n", s, x );

s = "7.8912654773d210";  
x = atof( s );  
printf( "atof test: ASCII string: %s\\tfloat: %e\\n", s, x );

s = " -9885 pigs";  
i = atoi( s );  
printf( "atoi test: ASCII string: %s\\t\\tinteger: %d\\n", s, i );

s = "98854 dollars";  
l = atol( s );  
printf( "atol test: ASCII string: %s\\t\\tlong: %ld\\n", s, l );  
\------------------------------------------------------------------------------------------------  
6. string to int ,long ,double              
int s;  
string str="123";  
stringstream ss;  
ss<<str;//从str输入  
ss>>s;//输出到int  
ss.clear();

——————————————————————————————————————————  
7. date to string  
\#include <time>  
using namespace std;

char dateStr \[9\];  
char timeStr \[9\];  
\_strdate( dateStr);  
printf( "The current date is %s \\n", dateStr);  
\_strtime( timeStr );  
printf( "The current time is %s \\n", timeStr);

\--------实践证明是正确的版本--------------------------------------------------------------

#include <iostream>
    #include <ctime>
    #include <cerrno>
    
    int main()
    {
         //Find the current time
         time_t curtime = time(0);
         
          //convert it to tm
          tm now=*localtime(&curtime);
        
         //BUFSIZ is standard macro that expands to a integer constant expression
         //that is greater then or equal to 256. It is the size of the stream buffer
         //used by setbuf()
         char dest[BUFSIZ]={
          0};
        
         //Format string determines the conversion specification's behaviour
         const char format[]="%A, %B %d %Y. The time is %X";
        
         //strftime - converts date and time to a string
         if (strftime(dest, sizeof(dest)-1, format, &now)>0)
           std::cout<<dest<<std::endl;
    
        else
           std::cerr<<"strftime failed. Errno code: "<<errno<<std::endl;
    }

|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||  
8.string to cstring

\+++++++++++++++++++++++++++++++++++++++++++++++++++++  
非Unicode下：  
int 转 CString：  
CString.Format("%d",int);  
...............................  
string 转 CString  
CString.format("%s", string.c\_str());  
用c\_str()确实比data()要好.  
.......................................  
char\* 转 CString  
CString.format("%s", char\*);  
CString strtest;  
char \* charpoint;  
charpoint="give string a value";  
strtest=charpoint; //直接付值  
.....................................................  
CString 转 int  
CString ss="1212.12";  
int temp=atoi(ss); //atoi \_atoi64或atol  
...................................................................................................................................  
9.在Unicode下的CString to double  
CSting sTemp("123.567");  
double dTemp = \_wtof(

[http_hi.baidu.com_cfans_blog_item_06970ef4b671f366dcc4745d.html]: http://hi.baidu.com/cfans/blog/item/06970ef4b671f366dcc4745d.html