String Function printf(format_string,arguments...)

Description

Demo Code


/* Copyright (c) 2005 Scott S. McCoy
 * This was originally a non-object oriented interface
* Function printf(format_string,arguments...)
 * Javascript emulation of the C printf function (modifiers and argument types 
 *    "p" and "n" are not supported due to language restrictions)
 *
 * Copyright 2003 K&L Productions. All rights reserved
 * http://www.klproductions.com /*from   ww w .  j  a  v  a 2s  . c  om*/
 *
 * Terms of use: This function can be used free of charge IF this header is not
 *               modified and remains with the function code.
 * 
 * Legal: Use this code at your own risk. K&L Productions assumes NO resposibility
 *        for anything.
 ********************************************************************************/

String.prototype.sprintf = function () {
  var fstring = this.toString();

  var pad = function(str,ch,len) { var ps='';
      for(var i=0; i<Math.abs(len); i++) {
          ps+=ch;
      }
      return len>0?str+ps:ps+str;
  };
  var processFlags = function(flags,width,rs,arg) { 
      var pn = function(flags,arg,rs) {
          if(arg>=0) { 
              if(flags.indexOf(' ')>=0) {
                  rs = ' ' + rs;
              } else if(flags.indexOf('+')>=0) {
                  rs = '+' + rs;
              }
          } else {
              rs = '-' + rs;
          }
          return rs;
      };
      var iWidth = parseInt(width,10);
      if(width.charAt(0) == '0') {
          var ec=0;
          if(flags.indexOf(' ')>=0 || flags.indexOf('+')>=0) {
              ec++;
          }
          if(rs.length<(iWidth-ec)) {
              rs = pad(rs,'0',rs.length-(iWidth-ec));
          }
          return pn(flags,arg,rs);
      }
      rs = pn(flags,arg,rs);
      if(rs.length<iWidth) {
          if(flags.indexOf('-')<0) {
              rs = pad(rs,' ',rs.length-iWidth);
          } else {
              rs = pad(rs,' ',iWidth - rs.length);
          }
      }    
      return rs;
  };
  var converters = [];
  converters.c = function(flags,width,precision,arg) { 
      if (typeof(arg) == 'number') {
          return String.fromCharCode(arg);
      } else if (typeof(arg) == 'string') {
          return arg.charAt(0);
      } else {
          return '';
      }
  };
  converters.d = function(flags,width,precision,arg) { 
      return converters.i(flags,width,precision,arg); 
  };
  converters.u = function(flags,width,precision,arg) { 
      return converters.i(flags,width,precision,Math.abs(arg)); 
  };
  converters.i =  function(flags,width,precision,arg) {
      var iPrecision=parseInt(precision, 10);
      var rs = ((Math.abs(arg)).toString().split('.'))[0];
      if(rs.length<iPrecision) {
          rs=pad(rs,' ',iPrecision - rs.length);
      }
      return processFlags(flags,width,rs,arg); 
  };
  converters.E = function(flags,width,precision,arg) {
      return (converters.e(flags,width,precision,arg)).toUpperCase();
  };
  converters.e = function(flags,width,precision,arg) {
      iPrecision = parseInt(precision, 10);
      if(isNaN(iPrecision)) {
          iPrecision = 6;
      }
      rs = (Math.abs(arg)).toExponential(iPrecision);
      if(rs.indexOf('.')<0 && flags.indexOf('#')>=0) {
          rs = rs.replace(/^(.*)(e.*)$/,'$1.$2');
      }
      return processFlags(flags,width,rs,arg);        
  };
  converters.f = function(flags,width,precision,arg) { 
      iPrecision = parseInt(precision, 10);
      if(isNaN(iPrecision)) {
          iPrecision = 6;
      }
      rs = (Math.abs(arg)).toFixed(iPrecision);
      if(rs.indexOf('.')<0 && flags.indexOf('#')>=0) {
          rs = rs + '.';
      }
      return processFlags(flags,width,rs,arg);
  };
  converters.G = function(flags,width,precision,arg) { 
      return (converters.g(flags,width,precision,arg)).toUpperCase();
  };
  converters.g = function(flags,width,precision,arg) {
      iPrecision = parseInt(precision, 10);
      absArg = Math.abs(arg);
      rse = absArg.toExponential();
      rsf = absArg.toFixed(6);
      if(!isNaN(iPrecision)) { 
          rsep = absArg.toExponential(iPrecision);
          rse = rsep.length < rse.length ? rsep : rse;
          rsfp = absArg.toFixed(iPrecision);
          rsf = rsfp.length < rsf.length ? rsfp : rsf;
      }
      if(rse.indexOf('.')<0 && flags.indexOf('#')>=0) {
          rse = rse.replace(/^(.*)(e.*)$/,'$1.$2');
      }
      if(rsf.indexOf('.')<0 && flags.indexOf('#')>=0) {
          rsf = rsf + '.';
      }
      rs = rse.length<rsf.length ? rse : rsf;
      return processFlags(flags,width,rs,arg);        
  };  
  converters.o = function(flags,width,precision,arg) { 
      var iPrecision=parseInt(precision, 10);
      var rs = Math.round(Math.abs(arg)).toString(8);
      if(rs.length<iPrecision) {
          rs=pad(rs,' ',iPrecision - rs.length);
      }
      if(flags.indexOf('#')>=0) {
          rs='0'+rs;
      }
      return processFlags(flags,width,rs,arg); 
  };
  converters.X = function(flags,width,precision,arg) { 
      return (converters.x(flags,width,precision,arg)).toUpperCase();
  };
  converters.x = function(flags,width,precision,arg) { 
      var iPrecision=parseInt(precision, 10);
      arg = Math.abs(arg);
      var rs = Math.round(arg).toString(16);
      if(rs.length<iPrecision) {
          rs=pad(rs,' ',iPrecision - rs.length);
      }
      if(flags.indexOf('#')>=0) {
          rs='0x'+rs;
      }
      return processFlags(flags,width,rs,arg); 
  };
  converters.s = function(flags,width,precision,arg) { 
      var iPrecision=parseInt(precision, 10);
      var rs = arg;
      if(rs.length > iPrecision) {
          rs = rs.substring(0,iPrecision);
      }
      return processFlags(flags,width,rs,0);
  };

  farr = fstring.split('%');
  retstr = farr[0];
  fpRE = /^([-+ #]*)(?:(\d*)\$|)(\d*)\.?(\d*)([cdieEfFgGosuxX])(.*)$/;
  for(var i = 1; i<farr.length; i++) { 
      fps=fpRE.exec(farr[i]);
      if(!fps) {
          continue;
      }
      var my_i = fps[2] ? fps[2] : i;
      if(arguments[my_i-1]) {
          retstr+=converters[fps[5]](fps[1],fps[3],fps[4],arguments[my_i-1]);
      }
      retstr += fps[6];
  }
  return retstr;
};
String Function printf(format_string,arguments...) - Node.js String

Description

Demo Code

Related Tutorials
