自定义打印输出函数格式，模拟printf函数

/*************************************************************      FileName : testPrintfFunction.cpp    FileFunc : printf参数模拟     Version  : V0.1      Author   : Sunrier      Date     : 2011-08-29Descp : 简单模拟printf函数*************************************************************/#include <stdio.h> #include <stdarg.h>#include <stdlib.h>//itoa()......#include <string.h>#include <math.h>#include <ctype.h>#defineMAXBUF15#defineDEFAULT_PRECI3//符点型默认精度  int add(const int ,...);int myPrintf(const char *, ...);void ftoa(double InputData, char *OutputData,int  DEFAULT_Vaule);int main ( void ){int x,y;//int x1=0xFEd278df;int x1=8989;double doubleData=89.78623;int x3=0;char *s1="1234567";x = add(4,1,2,3,4);y = add(3,1,2,3);printf("x=%B\n",x);printf("y=%3\n",y); myPrintf("Hello Sunrier!\n");myPrintf("wwwwwwwww");myPrintf("%s\n",s1);myPrintf("x3=%x\n",x3);myPrintf("x=%b\n",x);printf("x1=%b\n",x1);myPrintf("x1=%b\n",x1);myPrintf("x1=0x%x s=%s y=%d\n",x1,s1,y);myPrintf("doubleData=%f\n",doubleData);myPrintf("doubleData=%3f\n",doubleData);printf("doubleData=%3f\n",s1);return 0;} int add(const int n,...){va_list arg;//定义va_list类型变量argva_start(arg,n);//arg初始化,n是第一个可见参数名字;使arg指向第一个可选参数int sum=0;int tmp =0;for(int i=0;i<n;i++){tmp=va_arg(arg,int);//返回参数列表中的当前参数并使arg指向参数列表中的下一个参数sum+=tmp;}va_end(arg);//把arg指针清为NULLreturn sum;}int myPrintf(const char *format, ...){va_listap;va_start(ap,format);//STRING//char ch; const char *str; //const char *str1;//OCTint value ;char buf[MAXBUF];//HEXint offset;unsigned char ucI,ucLen;unsigned long ulValue;//unsigned char ucBuf[MAXBUF];//unsigned long *ulpValue;//FLOATdouble fdata;//BINARYwhile(*format){if('%'!=*format){putchar(*format++);continue;}switch(*++format){case's':str = NULL;str=va_arg(ap, const char *);for(;*str!='\0';str++){putchar(*str);}++format;//越过当前参数，移到下一个参数break;case'd':value=va_arg(ap,const int);memset(buf,0,sizeof(buf));itoa(value, buf, 10);for (str=buf ;*str!='\0'; str++) {putchar(*str);}++format;break;case'x':offset = 0;ucLen = 0 ;ulValue=va_arg(ap,const int);memset(buf,0,sizeof(buf));if( !ulValue ){buf[ucLen] = ulValue ;str = buf ;putchar((*str+48));++format;break;}for( ucI=0;ucI<MAXBUF;ucI++){if( pow(16,ucI)>ulValue ){ucLen = ucI;break;}}for( ucI=0;ucI<ucLen;ucI++){buf[ucI] = ulValue/pow(16,ucLen-ucI-1) ;ulValue = ulValue%(unsigned long)pow(16,ucLen-ucI-1);}//puts("0x");for (str=buf ;*str!='\0'; str++) {if( (*str>=0) && (*str<=9) ){putchar((*str+48));}else{putchar((*str+87));}}++format;break;case'X':offset = 0;ucLen = 0 ;ulValue=va_arg(ap,const int);memset(buf,0,sizeof(buf));if( !ulValue ){buf[ucLen] = ulValue ;str = buf ;putchar((*str+48));++format;break;}for( ucI=0;ucI<MAXBUF;ucI++){if( pow(16,ucI)>ulValue ){ucLen = ucI;break;}}for( ucI=0;ucI<ucLen;ucI++){buf[ucI] = ulValue/pow(16,ucLen-ucI-1) ;ulValue = ulValue%(unsigned long)pow(16,ucLen-ucI-1);}//puts("0X");for (str=buf ;*str!='\0'; str++) {if( (*str>=0) && (*str<=9) ){putchar((*str+48));}else{putchar((*str+55));}}++format;break;case'f':fdata = va_arg(ap, double);memset(buf,0,sizeof(buf));ftoa(fdata, buf, DEFAULT_PRECI);for (str=buf ;*str!='\0'; str++) {putchar(*str);}++format;break;case'.':if( isdigit(*++format) ){if( 'f'==(*++format) ){--format;fdata = va_arg(ap, double);memset(buf,0,sizeof(buf));int preci =*format-'0'; ftoa(fdata, buf, preci);for (str=buf ;*str!='\0'; str++) {putchar(*str);}++format;++format;}}else{--format;if( 'f'==(*++format) ){fdata = va_arg(ap, double);memset(buf,0,sizeof(buf));int preci =1; ftoa(fdata, buf, preci);for (str=buf ;*str!='\0'; str++) {putchar(*str);}++format;}}break;case'b':value=va_arg(ap,const int);memset(buf,0,sizeof(buf));itoa(value, buf, 2);for (str=buf ;*str!='\0'; str++) {putchar(*str);}++format;break;default:break;}}va_end(ap);return 0;}const double eps = 1e-12; char s[30]; void reverse(char *s){     int i , j;     int len = strlen(s);     for( i = 0 , j = len - 1 ; i < j ; i++ , j--)         s[i]^=s[j]^=s[i]^=s[j];} /* ftoa:   convert double n to string s with digits*/void ftoa(double n, char *s,  int  digits){     memset(s , 0 , sizeof(s));     int i = 0 , p;     bool sign = true;     if( n < 0 )      {          sign = false;         n = -n;     }     long   t = ( long)n;     n = n - t;     if( t == 0)     {         s[i++] = '0';     }     else     {         while( t != 0 )         {             p = t % 10;             t /= 10;             s[i++] = p + '0';         }         if(!sign) s[i++] = '-';         reverse(s);     }     if( fabs( n - 0.0 ) > eps )     {         s[i++] = '.';         int cur_d = 0;         while( cur_d < digits)         {             cur_d++;             n *= 10.0;             p = (long )n;             n = n - p;             s[i++] = p + '0';         }     }     s[i] = '\0';}