a_printf.cpp

一个不错

/* Copyright is licensed under GNU LGPL.                 by I.J.Wang 2006

  Compare the difference and use in printf/sscanf fassion

  Build: make a_printf
*/

#include "../src/wy_uty.h"
#include <cstdio>       // printf/sscanf is used for comparison

static void sim_printf(void)
{
 WyRet r;
 WyStr str;

 // printf("%d",val)
 {
  int val=1289;
  std::printf("%d\n",val);   // for comparison
  str=Wy::wrd(val);
  Wy::cout << str << " --- " << val << "--\n";
 }

 // printf("%5d",val)
 {
  int val=1289;
  std::printf("%5d\n",val);   // for comparison
  str=Wy::wrd(val);
  if(str.size()<5) {
    if((r=str.insert(0,5-str.size(),' '))!=Ok) {
      WY_THROW(r);
    }
  }
  Wy::cout << str << " --- " << val << "--\n";
 }

 // printf("%-6d",val)
 {
  int val=-189;
  std::printf("%-6d\n",val);   // for comparison
  str=Wy::wrd(val);
  if(str.size()<6) {
    if((r=str.append(6-str.size(),' '))!=Ok) {
      WY_THROW(r);
    }
  }
  Wy::cout << str << " --- " << val << "--\n";
 }

 // printf("%06d",val)
 {
  int val=189;
  std::printf("%06d\n",val);   // for comparison
  str=Wy::wrd(val);
  if(str.size()<6) {
    if((r=str.insert(0,6-str.size(),'0'))!=Ok) {
      WY_THROW(r);
    }
  }
  Wy::cout << str << " --- " << val << "--\n";
 }

 // printf("%.2f",val)
 {
  float val=189.189;
  std::printf("%.2f\n",val);   // for comparison
  str=Wy::wrd(val,10,2);
  Wy::cout << str << " --- " << val << "--\n";
 }

 // printf("%.2g",val)
 {
  float val=189.189;
  std::printf("%.2g\n",val);   // for comparison
  str=Wy::wrd(val,0,2);
  Wy::cout << str << " --- " << val << "--\n";
 }
};

static void sim_sscanf(void)
{
 const char Input1[]=" 12.34	 345.67E-1	 78.901e1 555";
 WyRet r;

  // sscanf("%f %f %lf %d",..)
  {
    const WyCSeg txt=Input1;
    size_t fidx=0;
    float value_f1,value_f2;
    double value_lf;
    int   value_d;

    // This loop is to use break to exit the block to 
    // simulate sscanf (loop exactly once)
    //
    do {
      // convert the 1st word and print the result
      if((r=Wy::_scanum(value_f1,fidx,txt))!=Ok) {
        WY_HERE(r);
        break;
      }
      Wy::cout << value_f1 << ", ";

      // convert the 2nd word and print the result
      if((r=Wy::_scanum(value_f2,fidx,txt))!=Ok) {
        WY_HERE(r);
        break;
      }
      Wy::cout << value_f2 << ", ";

      // convert the 3rd word and print the result
      if((r=Wy::_scanum(value_lf,fidx,txt))!=Ok) {
        WY_HERE(r);
        break;
      }
      Wy::cout << value_lf << ", ";

      // convert the 4th word and print the result
      if((r=Wy::_scanum(value_d,fidx,txt))!=Ok) {
        WY_HERE(r);
        break;
      }
      Wy::cout << value_d << "\n";

      r=Ok;
    } while(false);
 
    if(r!=Ok) {
      WY_THROW(r);
    }
    
    // compare by printing the result from std::sscanf
    if(std::sscanf(txt.begin(),"%f %f %lf %d",
                   &value_f1,&value_f2,&value_lf,&value_d)!=4) {
      WY_THROW( WyRet() );
    }
    Wy::cout << value_f1 << ", " << value_f2 << ", "
             << value_lf << ", " << value_d << '\n';
  }
};

int main(void)
try {
 sim_printf();
 sim_sscanf();
 return(0);
}
catch(const WyRet& e) {
 Wy::cerr << Wy::wrd(e) << '\n';
 throw;
}
catch(...) {
 Wy::cerr << "unknown throw type\n";
 throw;
};