Initial commit

c++/Others/Read Text Files.cpp

@@ -0,0 +1,105 @@
+Read Text Files
+
+void main()
+{
+ char pcMyLines[10000];
+
+ ReadLines("C:\\MyTestFile.txt", 10, 5, pcMyLines, 12345);
+}
+
+// This function reads n lines from a file
+// Returns the amount of bytes read
+int ReadLines(const char *pcFile, const int iStartLine, const int iTotLines, char *pcBuffer, const int iBufLen)
+{
+ FILE *fSrc;
+ int   iLines = 0, j, iPos, iByteCount = 0;
+
+ // Try to open the file
+ if(fSrc = fopen(pcFile, "r"))
+ {
+   // Try to locate the starting line
+   if(iPos = GetLinePos(fSrc, iStartLine))
+   {
+     // Set the starting position
+     if(!fseek(fSrc, iPos, SEEK_SET))
+     {
+       // Read the lines
+       for(iLines=0;iLines<iTotLines;iLines++)
+       {
+         // Read the line
+         if((j = ReadLine(fSrc, iPos, pcBuffer, iBufLen - iByteCount)) == -1) break;
+         iByteCount += j;
+       }
+     }
+   }
+
+   // Close the file
+   fclose(fSrc);
+ }
+
+ // Return the amount of bytes in the buffer, or -1 for failure
+ return iLines == iTotLines ? iByteCount : -1;
+}
+
+
+// This function reads a single line from a file
+int ReadLine(FILE *fSrc, const int iStartPos, char *pcBuffer, const int iBufLen)
+{
+ int iCount = 0;
+
+ // Set the starting position
+ if(!fseek(fSrc, iStartPos, SEEK_SET))
+ {
+   // Keep reading characters while we can
+   while(!feof(fSrc) && (iCount < iBufLen))
+   {
+     // Read the character
+     pcBuffer[iCount] = (char)fgetc(fSrc);
+     if(pcBuffer[iCount++] == '\n') break;
+   }
+ }
+ else iCount = -1;
+
+ return iCount;
+}
+
+// This function locates a line in a file
+// Returns the position of the line in the file
+int GetLinePos(FILE *fSrc, const int iLine, const int iStartPos /* 0 */)
+{
+ char  pcBuffer[4096];
+ int   i, iPos = 0, iLines = 0, iBytes;
+
+ // Set the start position
+ if(!fseek(fSrc, iStartPos, SEEK_SET))
+ {
+   // Read the (next) block of data
+   while(iBytes = fread(pcBuffer, sizeof(char), 4096, fSrc))
+   {
+     // Go through the block
+     for(i=0;i<iBytes;i++)
+     {
+       // Do we have a new line?
+       if(pcBuffer[i] == '\n')
+       {
+         // Update the line count
+         iLines++;
+
+         // Have we reached the desired line?
+         if(iLines == iLine)
+         {
+           // Store the position
+           iPos += i;
+           break;
+         }
+       }
+     }
+
+     // Update the position
+     iPos += iBytes;
+   }
+ }
+
+ // Return the position of the line in the file, or -1 for failure
+ return iLines == iLine ? iPos : -1;
+}