add ipi10

ws2019/ipi/uebungen/readfiles.cpp

@@ -0,0 +1,39 @@
+#include <fstream>
+#include <iostream>
+#include <string>
+
+using namespace std;
+
+int main(int argc, char* argv[]) {
+    // check if correct argument count
+    if (argc < 2) {
+        printf("Dateiname erwartet\n");
+        return 1;
+    }
+
+    // get filename from argument list
+    string filename = argv[1];
+    // open input file
+    ifstream fileIn;
+    fileIn.open(filename + ".txt");
+    // open output file
+    ofstream fileOut;
+    fileOut.open(filename + "-a.txt");
+    // check if we could open the files
+    if (!fileIn.good() || !fileOut.good()) {
+        // could not open files
+        cout << "Konnte Datei " + filename + ".txt nicht lesen" << endl;
+        return 1;
+    }
+    string input; // variable containing line
+    int lineNo = 1; // count lines
+    while(getline(fileIn, input)) { // while there is still a line left
+        // write out line with prepended line number to output file
+        fileOut << to_string(lineNo) + ": " + input << endl;
+        // increment line counter
+        lineNo += 1;
+    }
+    // close files
+    fileIn.close();
+    fileOut.close();
+}