C language file operation: How to handle text files?
Apr 04, 2025 am 10:18 AM
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 NULLRead 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;
}The above is the detailed content of C language file operation: How to handle text files?. For more information, please follow other related articles on the PHP Chinese website!
Hot AI Tools
Undress AI Tool
Undress images for free
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Clothoff.io
AI clothes remover
Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!
Hot Article
Hot Tools
Notepad++7.3.1
Easy-to-use and free code editor
SublimeText3 Chinese version
Chinese version, very easy to use
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
SublimeText3 Mac version
God-level code editing software (SublimeText3)
Hot Topics
C language data structure: data representation and operation of trees and graphs
Apr 04, 2025 am 11:18 AM
C language data structure: The data representation of the tree and graph is a hierarchical data structure consisting of nodes. Each node contains a data element and a pointer to its child nodes. The binary tree is a special type of tree. Each node has at most two child nodes. The data represents structTreeNode{intdata;structTreeNode*left;structTreeNode*right;}; Operation creates a tree traversal tree (predecision, in-order, and later order) search tree insertion node deletes node graph is a collection of data structures, where elements are vertices, and they can be connected together through edges with right or unrighted data representing neighbors.
How debian readdir integrates with other tools
Apr 13, 2025 am 09:42 AM
The readdir function in the Debian system is a system call used to read directory contents and is often used in C programming. This article will explain how to integrate readdir with other tools to enhance its functionality. Method 1: Combining C language program and pipeline First, write a C program to call the readdir function and output the result: #include#include#include#includeintmain(intargc,char*argv[]){DIR*dir;structdirent*entry;if(argc!=2){
The truth behind the C language file operation problem
Apr 04, 2025 am 11:24 AM
The truth about file operation problems: file opening failed: insufficient permissions, wrong paths, and file occupied. Data writing failed: the buffer is full, the file is not writable, and the disk space is insufficient. Other FAQs: slow file traversal, incorrect text file encoding, and binary file reading errors.
C language multithreaded programming: a beginner's guide and troubleshooting
Apr 04, 2025 am 10:15 AM
C language multithreading programming guide: Creating threads: Use the pthread_create() function to specify thread ID, properties, and thread functions. Thread synchronization: Prevent data competition through mutexes, semaphores, and conditional variables. Practical case: Use multi-threading to calculate the Fibonacci number, assign tasks to multiple threads and synchronize the results. Troubleshooting: Solve problems such as program crashes, thread stop responses, and performance bottlenecks.
CS-Week 3
Apr 04, 2025 am 06:06 AM
Algorithms are the set of instructions to solve problems, and their execution speed and memory usage vary. In programming, many algorithms are based on data search and sorting. This article will introduce several data retrieval and sorting algorithms. Linear search assumes that there is an array [20,500,10,5,100,1,50] and needs to find the number 50. The linear search algorithm checks each element in the array one by one until the target value is found or the complete array is traversed. The algorithm flowchart is as follows: The pseudo-code for linear search is as follows: Check each element: If the target value is found: Return true Return false C language implementation: #include#includeintmain(void){i
How to understand ABI compatibility in C?
Apr 28, 2025 pm 10:12 PM
ABI compatibility in C refers to whether binary code generated by different compilers or versions can be compatible without recompilation. 1. Function calling conventions, 2. Name modification, 3. Virtual function table layout, 4. Structure and class layout are the main aspects involved.
How to output a countdown in C language
Apr 04, 2025 am 08:54 AM
How to output a countdown in C? Answer: Use loop statements. Steps: 1. Define the variable n and store the countdown number to output; 2. Use the while loop to continuously print n until n is less than 1; 3. In the loop body, print out the value of n; 4. At the end of the loop, subtract n by 1 to output the next smaller reciprocal.
How to define the call declaration format of c language function
Apr 04, 2025 am 06:03 AM
C language functions include definitions, calls and declarations. Function definition specifies function name, parameters and return type, function body implements functions; function calls execute functions and provide parameters; function declarations inform the compiler of function type. Value pass is used for parameter pass, pay attention to the return type, maintain a consistent code style, and handle errors in functions. Mastering this knowledge can help write elegant, robust C code.
