字符串，整形数，浮点数之间的转换

一  字符串转化为整形数

//函数名:   atoi   
//功     能:   把字符串转换成整形数
//用     法:   int   atoi(const   char   *nptr);   
//程序例:   
#include   <stdlib.h>   
#include   <stdio.h>   

int   main(void)   
{   
      int   n;   
      char   *str   =   "12345.67 ";   
      n   =   atoi(str);   
  printf( "integer   =   %d\n ",n); 
      return   0;   
} 

二 字符串转化为浮点数

//函数名:   atof   
//功     能:   把字符串转换成浮点数 
//用     法:   int   atof(const   char   *nptr);   
//程序例:   
#include   <stdlib.h>   
#include   <stdio.h>   

int   main(void)   
{   
      float   n;   
      char   *str   =   "12345.67 ";   
      n   =   atof(str);   
  printf( "integer   =   %f\n ",n); 
      return   0;   
} 

三 系列转化

#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   ); 
}