[英]How to write back to a csv file that was just read (c++)?
我試圖寫回以前在程序中讀取過的csv文件。 該程序當前如下所示:
ifstream file;
file.open ("file");
e=0;
while (file.good()) {
getline ( file, infor,',');
istringstream (infor) >> infoc;
var1[e]=infoc;
getline ( file, infor,',');
istringstream (infor) >> infoc;
var2[e]=infoc;
getline ( file, infor,',');
istringstream (infor) >> infoc;
var3[e]=infoc;
getline ( file, infor,',');
istringstream (infor) >> infoc;
var4[e]=infoc;
getline ( file, infor,',');
istringstream (infor) >> infoc;
var5[e]=infoc;
getline ( file, infor,',');
istringstream (infor) >> infoc;
var6[e]=infoc;
getline ( file, infor,',');
istringstream (infor) >> infoc;
var7[e]=infoc;
getline ( file, infor,',');
istringstream (infor) >> infoc;
var8[e]=infoc;
getline ( file, infor,',');
istringstream (infor) >> infoc;
var9[e]=infoc;
getline ( file, infor,',');
istringstream (infor) >> infoc;
var10[e]=infoc;
getline ( file, infor,',');
istringstream (infor) >> infoc;
var11[e]=infoc;
getline ( file, infor,',');
istringstream (infor) >> infoc;
var12[e]=infoc;
getline ( file, infor,',');
istringstream (infor) >> infoc;
var13[e]=infoc;
getline ( file, infor,',');
istringstream (infor) >> infoc;
var14[e]=infoc;
getline ( file, infor,',');
istringstream (infor) >> infoc;
var15[e]=infoc;
++e;
}
var1[e] = var1[e] + v1;
var2[e] = var2[e] + v2;
var3[e] = var3[e] + v3;
var4[e] = var4[e] + v4;
var5[e] = var5[e] + v5;
var6[e] = var6[e] + v6;
var7[e] = var7[e] + v7;
var8[e] = var8[e] + v8;
var9[e] = var9[e] + v9;
var10[e] = var10[e] + v10;
var11[e] = var11[e] + v11;
var12[e] = var12[e] + v12;
var13[e] = var13[e] + v13;
var14[e] = var14[e] + v14;
var15[e] = var15[e] + v15;
//WRITE TO compYTD
file.close();
在關閉文件之前,我想將新計算出的變量寫回到文件中,以擦除以前讀取的所有內容。 是否有允許我執行此操作的功能? 還有一個單獨的功能可以讓我寫回該文件,並添加到已經存在的行中嗎?
我個人將關閉文件,然后使用類似以下內容的新值:
ofstream ofile("file.csv");
for(int i = 0; i < e; i++)
ofile << var1[i] << ", " << var2[i] << ", " << var3[i] << ", " << ... endl;
ofile.close();
(當然,如果將var1
, var2
等放在數組或向量中會更容易-當然,在讀取時也是如此-只是getline
, istringstream
等的一個實例)
要附加文件(在文件末尾添加信息),可以使用ios_base::app
作為ofstream
的標志。 因此,再次關閉輸入文件,並在ofstream
打開輸出:
ofstream ofile("file.csv", ios_base::app);
您寫入文件的所有內容都將位於文件末尾。
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