How to Read Numeric Data from a Text File in C ?

Reading Numeric Data from a Text File in C

If you have a text file containing numeric data, you may want to read it and assign the numbers to variables in C for further processing. This can be achieved using C 's file handling capabilities.

To read numeric data from a text file, follow these steps:

1. Open the Text File:

   ifstream myfile;
   myfile.open("data.txt");

2. Read the Data:
   There are two main approaches to reading numeric data:

   • Using Stream Extraction Operator (>>) Repeatedly:

     float a;
     while (myfile >> a) {
       // Process the value of 'a' here...
     }

     This method repeatedly reads numbers from the file until it reaches the end of file.

   • Reading Multiple Values Using Chained Extraction Operators:

     float a, b, c, d, e, f;
     myfile >> a >> b >> c >> d >> e >> f;

     This method reads multiple values in one go if you know the exact number of elements in the file.

3. Close the Text File:

   myfile.close();

Handling Text Files with Spaces:

In the example text file mentioned in the problem, numbers are separated by spaces. To handle this, you can:

• Use the getline() function to read a line of text at a time and then extract the numbers using stringstream.
• Use a loop to iterate through the line and read the numbers using the stream extraction operator (>>).

Specific Value or Skipping Values:

If you need to read a specific value or skip values in the file, you can:

• For a Specific Value: Use a loop to read and discard values until you reach the desired location.
• For Skipping Values: Use a loop to skip a specified number of values before reading the desired data.

By following these steps, you can effectively read numeric data from a text file and assign it to variables in C .

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