任何一個文件在使用之前和使用之後, 必須要進行打開和關閉
istream,ostream,cin.get(),cin.getline(),cin.read(),cout.write()
fopen,fgetc(),fputc(),getc(),putc(),fgets(),fputs()
getchar(),putchar(),gets(),puts()
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
char infile[255],outputfile[255];
FILE *inf,*outf;
strcpy(filename,m_strYuan);
strcpy(outputfile,m_strYasuo);
inf =fopen(infile,"rb");
outf=fopen(outputfile,"wb");
int ch;
while((ch=fgetc(fp))!=EOF)
{
cal[ch]++;
in_num++;
}
fclose(fp);
fputc(T.leafnum,outf);
fseek(outf,3*T.leafnum,0);
fputc(B.count,outf);
fclose(fp);
=======================================================================================================
ofstream outQuanFile( "權值.txt", ios::out );
for(int j1=0;j1<HN;j1++)
{
outQuanFile<<"U12["<<i1<<"]["<<j1<<"]="<<U12[i1][j1]<<" ";
}
outQuanFile<<"/n";
for(int j3=0;j3<HN;j3++)
{
outQuanFile<<"V["<<i3<<"]["<<j3<<"]="<<V[i3][j3]<<" ";
}
outQuanFile<<"/n";
outQuanFile.close();
========================================================================================================
ifstream GetTrainingData ( "訓練樣本.txt", ios::in );
for(int m=0;m<N;m++)
{
for(int i=0;i<IN;i++)
{
GetTrainingData>>Study_Data[m].input[i]; //取得輸入數據
}
for(int j=0;j<ON;j++)
{
GetTrainingData>>Study_Data[m].teach[j]; //取得輸出數據
}
}
GetTrainingData.close();
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
在某些場合下,我們需要把輸入流當作一個未經解釋的字節序來讀取,而不是特定的數據類型(如char,int,string)的序列
istream的成員函數get()一次讀入一個字節,getline()一次讀入一塊字節,或者由一個換行符作爲結束,或者由某個用戶定義的終止字符作爲結束.
1. get(char& ch):從輸入流中提取一個字符,包括空白字符,並將它存儲在ch中.(回車,空格都算)
char ch; while( cin.get(ch) ) { ... }; cout.put(ch);
2. get() :從輸入流輸入一個字符,它返回字符值而不是並應用的istream對象.返回類型是int而非char.
3. get(char *sink, streamsize size, char delimiter='/n')//(字符數組,最大數目,結束符),在第二個get之前一定要去掉delimiter,cin.ignore();delimiter不會被放在數組中,而是留作istream的下一個字符.
cin.get(line,max_line); get_count=cin.gcount();//實際讀入個數 cin.ignore();
*** cin.getline(char *sink, streamsize size, char delimiter='/n'),它自己丟棄delimiter,cin.getline( ... )
cin.read(char *addr, streamsize size);//從輸入流提取size個連續的字節,放入addr;
cout.write(const char *sink, streamsize lenth);//(要顯示字符個數)
標準庫的getline可以輸入到一個string對象中
getline(istream &is, string str, char delimiter);
----------------------------------------------------------------------
ofstream outfile("copy.out", ios_base::out);//ios_base::app
試圖讀寫文件之前,先判斷它是否已成功打開
if( ! outfile){ cerr<<"cannot open copy.out for output /n"; exit(-1); }
ifstream infile("inputf.txt", ios_base::in);
if(!infile) { cerr<<"cannot open input file /n"};
infile<<name[20]<<score;
outfile<<name[20]<<" "<<score;
----------------------------------------------------------------------
FILE *fopen( const char *fname, const char *mode );//(文件名,打開模式)
"r" 打開一個用於讀取的文本文件
"w" 創建一個用於寫入的文本文件
"a" 附加到一個文本文件
"rb" 打開一個用於讀取的二進制文件
"wb" 創建一個用於寫入的二進制文件
1)讀寫字符
int fgetc(FILE *stream);//返回stream流的下一個字符,整形
int fputc( int ch, FILE *stream );//把字符ch輸出到輸出流
while( (ch=fgetc(inF)) != EOF) { cout<<ch<<endl; fputc(ch,outF); }
(getc與fgetc相同,put與fputc相同)
2)讀寫字符串
char *fgets( char *str, int num, FILE *stream );//(字符串,個數,文件)
int fputs( const char *str, FILE *stream ); //(字符串,寫入文件)
3)
int getchar( void ); //從STDIN(標準輸入)獲取並返回下一個字符
int putchar( int ch ); //把ch寫到STDOUT(標準輸出).
4)
char *gets( char *str );//從STDIN(標準輸入)讀取字符並把它們加載到str(字符串)裏,直到遇到新行(/n)或到達EOF
int puts( char *str ); //把str(字符串)寫到STDOUT(標準輸出)上