How to read word from file

In this article, we are going to learn How to Read text File word by word in C. We will read each word from the text file in each iteration.

C fscanf Function

The fscanf() function is available in the C library. This function is used to read formatted input from a stream. The syntax of the fscanf function is:

Syntax

int fscanf(FILE *stream, const char *format, ...)

Parameters :

• stream − This is the pointer to a FILE object that identifies the stream.
• format − This is the C string that contains one or more of the following items − Whitespace character, Non-whitespace character, and Format specifiers.
• A format specifier will be as [=%[*][width][modifiers]type=].

1. Read File Word by Word in C using fscanf Function

Here we are making use of the fscanf function to read the text file. The first thing we are going to do is open the file in reading mode. So using fopen() function and “r” read mode we opened the file. The next step is to find the file stats like what is the size of the data this file contains. so we can allocate exact memory for the buffer that is going to hold the content of this file. We are using the stat() function to find the file size.

• Once we have the size and buffer allocated for this size, we start reading the file by using the fscanf() function.
• We keep reading the file word by word until we reach the end of file.In fscanf function, we are passing “%39[^-n] as the argument so we can read the text until we find the next word.
• The code will look like this:

fscanf(in_file, "%39[^-n]", file_contents)

C Program to Read text File word by word

To run this program, we need one text file with the name Readme.txt in the same folder where we have our code.The content of the file is:

Hello My name is 
John 
danny

#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>

const char* filename = "Readme.txt";

int main(int argc, char *argv[])
{
    FILE *in_file = fopen(filename, "r");
    if (!in_file) 
	{
        perror("fopen");
        return 0;
    }

    struct stat sb;
    if (stat(filename, &sb) == -1) 
	{
        perror("stat");
        return 0;
    }

    char *file_contents = malloc(sb.st_size);

    while (fscanf(in_file, "%[^-n ] ", file_contents) != EOF) {
      printf("> %sn", file_contents);
	  }
    
	

    fclose(in_file);
    return 0;
}

Output

Hello
My
name
is
John
danny

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Prerequisites: File Handling in Python Given a text file and the task is to read the information from file word by word in Python. Examples:

Input: I am R2J! Output: I am R2J! Input: Geeks 4 Geeks And in that dream, we were flying. Output: Geeks 4 Geeks And in that dream, we were flying.

Approach:

1. Open a file in read mode which contains a string.
2. Use for loop to read each line from the text file.
3. Again use for loop to read each word from the line splitted by ‘ ‘.
4. Display each word from each line in the text file.

Example 1: Let’s suppose the text file looks like this – Text File:  

Output:

Geeks
4
geeks

Time Complexity: O(n), where n is the total number of words in the file.
Auxiliary Space: O(1), as the program is reading and displaying each word one by one without storing any additional data.

Example 2: Let’s suppose the text file contains more than one line. Text file:  

Output:

Geeks
4
Geeks
And
in
that
dream,
we
were
flying.

Time complexity: O(n), where n is the total number of words in the file.
Auxiliary space: O(1), as only a constant amount of extra space is used to store each word temporarily while printing it.

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Summary: in this tutorial, you will learn how to read from a text file using standard library functions such as fgetc() and fgets().

Steps for reading from a text file

To read from a text file, you follow these steps:

• First, open the text file using the fopen() function.
• Second, use the fgets() or fgetc() function to read text from the file.
• Third, close the file using the fclose() function.

Reading from a text file one character at a time

To read from a text file one character at a time, you use the fgetc() function.

The following program reads from the readme.txt file one character at a time and display the file contents to the output:

#include <stdio.h>

int main()
{
    char *filename = "readme.txt";
    FILE *fp = fopen(filename, "r");

    if (fp == NULL)
    {
        printf("Error: could not open file %s", filename);
        return 1;
    }

    // read one character at a time and
    // display it to the output
    char ch;
    while ((ch = fgetc(fp)) != EOF)
        putchar(ch);

    // close the file
    fclose(fp);

    return 0;
}
Code language: C++ (cpp)

Reading from a text file line by line

To read a line from a text file, you use the fgets() function:

char * fgets ( char *str, int num, FILE *stream );
Code language: C++ (cpp)

The fgets() function reads characters from the stream and store them into the str.

The fgets() function stops reading if:

• num-1 characters have been read
• the newline character or end-of-file character reached.

Note that the fgets() function also includes the newline character in the str.

The following example shows how to use the fgets() function to read a text file line by line and display the text to the output:

#include <stdio.h>

int main()
{
    char *filename = "readme.txt";
    FILE *fp = fopen(filename, "r");

    if (fp == NULL)
    {
        printf("Error: could not open file %s", filename);
        return 1;
    }

    // reading line by line, max 256 bytes
    const unsigned MAX_LENGTH = 256;
    char buffer[MAX_LENGTH];

    while (fgets(buffer, MAX_LENGTH, fp))
        printf("%s", buffer);

    // close the file
    fclose(fp);

    return 0;
}
Code language: C++ (cpp)

Summary

• Use the fgetc() function to read from a text file, a character at a time.
• Use the fgets() function to read from a text file, line by line.

Summary: in this tutorial, you learn various ways to read text files in Python.

TL;DR

The following shows how to read all texts from the readme.txt file into a string:

with open('readme.txt') as f:
    lines = f.readlines()Code language: Python (python)

Steps for reading a text file in Python

To read a text file in Python, you follow these steps:

• First, open a text file for reading by using the open() function.
• Second, read text from the text file using the file read(), readline(), or readlines() method of the file object.
• Third, close the file using the file close() method.

1) open() function

The open() function has many parameters but you’ll be focusing on the first two:

open(path_to_file, mode)Code language: Python (python)

The path_to_file parameter specifies the path to the text file.

If the program and file are in the same folder, you need to specify only the filename of the file. Otherwise, you need to include the path to the file as well as the filename.

To specify the path to the file, you use the forward-slash ('/') even if you’re working on Windows.

For example, if the file readme.txt is stored in the sample folder as the program, you need to specify the path to the file as c:/sample/readme.txt

The mode is an optional parameter. It’s a string that specifies the mode in which you want to open the file. The following table shows available modes for opening a text file:

For example, to open a file whose name is the-zen-of-python.txt stored in the same folder as the program, you use the following code:

 f = open('the-zen-of-python.txt','r')Code language: Python (python)

The open() function returns a file object which you will use to read text from a text file.

2) Reading text methods

The file object provides you with three methods for reading text from a text file:

• read(size) – read some contents of a file based on the optional size and return the contents as a string. If you omit the size, the read() method reads from where it left off till the end of the file. If the end of a file has been reached, the read() method returns an empty string.
• readline() – read a single line from a text file and return the line as a string. If the end of a file has been reached, the readline() returns an empty string.
• readlines() – read all the lines of the text file into a list of strings. This method is useful if you have a small file and you want to manipulate the whole text of that file.

3) close() method

The file that you open will remain open until you close it using the close() method.

It’s important to close the file that is no longer in use for the following reasons:

• First, when you open a file in your script, the file system usually locks it down so no other programs or scripts can use it until you close it.
• Second, your file system has a limited number of file descriptors that you can create before it runs out of them. Although this number might be high, it’s possible to open a lot of files and deplete your file system resources.
• Third, leaving many files open may lead to race conditions which occur when multiple processes attempt to modify one file at the same time and can cause all kinds of unexpected behaviors.

The following shows how to call the close() method to close the file:

f.close()Code language: Python (python)

To close the file automatically without calling the close() method, you use the with statement like this:

with open(path_to_file) as f:
    contents = f.readlines()Code language: Python (python)

In practice, you’ll use the with statement to close the file automatically.

Reading a text file examples

We’ll use the-zen-of-python.txt file for the demonstration.

The following example illustrates how to use the read() method to read all the contents of the the-zen-of-python.txt file into a string:

with open('the-zen-of-python.txt') as f:
    contents = f.read()
    print(contents)Code language: Python (python)

Output:

Beautiful is better than ugly.
Explicit is better than implicit.
Simple is better than complex.
...Code language: Python (python)

The following example uses the readlines() method to read the text file and returns the file contents as a list of strings:

with open('the-zen-of-python.txt') as f:
    [print(line) for line in f.readlines()]Code language: Python (python)

Output:

Beautiful is better than ugly.

Explicit is better than implicit.

Simple is better than complex.

Complex is better than complicated.

...Code language: Python (python)

The reason you see a blank line after each line from a file is that each line in the text file has a newline character (n). To remove the blank line, you can use the strip() method. For example:

with open('the-zen-of-python.txt') as f:
    [print(line.strip()) for line in f.readlines()]Code language: Python (python)

The following example shows how to use the readline() to read the text file line by line:

with open('the-zen-of-python.txt') as f:
    while True:
        line = f.readline()
        if not line:
            break
        print(line.strip())Code language: Python (python)

Output:

Explicit is better than implicit.
Complex is better than complicated.
Flat is better than nested.
...Code language: Python (python)

A more concise way to read a text file line by line

The open() function returns a file object which is an iterable object. Therefore, you can use a for loop to iterate over the lines of a text file as follows:

with open('the-zen-of-python.txt') as f:
    for line in f:
        print(line.strip())Code language: Python (python)

This is a more concise way to read a text file line by line.

Read UTF-8 text files

The code in the previous examples works fine with ASCII text files. However, if you’re dealing with other languages such as Japanese, Chinese, and Korean, the text file is not a simple ASCII text file. And it’s likely a UTF-8 file that uses more than just the standard ASCII text characters.

To open a UTF-8 text file, you need to pass the encoding='utf-8' to the open() function to instruct it to expect UTF-8 characters from the file.

For the demonstration, you’ll use the following quotes.txt file that contains some quotes in Japanese.

The following shows how to loop through the quotes.txt file:

with open('quotes.txt', encoding='utf8') as f:
    for line in f:
        print(line.strip())Code language: Python (python)

Output:

Summary

• Use the open() function with the 'r' mode to open a text file for reading.
• Use the read(), readline(), or readlines() method to read a text file.
• Always close a file after completing reading it using the close() method or the with statement.
• Use the encoding='utf-8' to read the UTF-8 text file.