C language file operation: How to handle text files?
In C, file operations allow us to store and retrieve data, including text files. To process text files, you must first use fopen() to open the file, then use fgets() to read it line by line, write it with fputs(), and finally use fclose() to close the file.
C language file operation: text file processing
In C programming, we can operate on files, including text files. File operations allow us to store and retrieve data, thus creating more complex applications.
Open the file
To process a text file, you first need to use the fopen()
function to open the file. This function returns a file pointer that can be used to perform file operations.
FILE *fp = fopen("textfile.txt", "r"); // Open the file for reading ("r") // Open if the file exists, otherwise return NULL
Read the file
After opening the file, we can use the fgets()
function to read the file line by line. fgets()
will read a row and store it in the specified buffer.
char buffer[256]; while (fgets(buffer, sizeof(buffer), fp)) { // Process each row of data}
Write to a file
To write to a text file, use the fputs()
function. This function writes a string to a file.
FILE *fp = fopen("textfile.txt", "w"); // Open the file and write ("w") // Overwrite if the file exists, otherwise create a new file fputs("This is a sample line to write to a text file.", fp);
Close the file
Finally, after completing the operation on the file, please use the fclose()
function to close the file.
fclose(fp);
Practical cases
The following program reads the text file "textfile.txt" and prints its contents:
#include <stdio.h> int main() { FILE *fp = fopen("textfile.txt", "r"); if (fp == NULL) { perror("Cannot open file"); return -1; } char buffer[256]; while (fgets(buffer, sizeof(buffer), fp)) { printf("%s", buffer); } fclose(fp); return 0; }
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