How to Prevent Double Reads When Reading Integers from a File in C ?

Reading Integers from a File Until EOF: Avoiding Double Reads

The provided C code reads integers from a text file until it reaches the end of file (EOF). However, it reads the last line twice, resulting in a repetition in the output. This occurs because:

• Upon reading the last integer (30 in the example) and checking for EOF, the EOF mark remains unread.
• In the next iteration, the same integer (30) is still stored in the input buffer, and EOF is correctly detected.
• The integer is output twice: once from the previous iteration's buffer and again from the current EOF check.

Solution:

To fix this issue, use a while loop that exits upon reading EOF:

while (true) {
    int x;
    iFile >> x;
    if (iFile.eof()) break;
    cerr << x << endl;
}

In this loop:

• The integer is read into the buffer.
• If EOF is reached, the loop exits.
• Otherwise, the integer is output to standard error.

This approach ensures that the last integer is printed only once.

Note:

The original code had another potential issue: attempting to read an empty file. This can be resolved by embedding the read operation within an if-statement that checks if the stream is open and not at EOF.

The above is the detailed content of How to Prevent Double Reads When Reading Integers from a File in C ?. For more information, please follow other related articles on the PHP Chinese website!