5+ Fgets 使い方 For You

C Programming FAQ 1 Using fgets and sscanf to restrict input YouTube from www.youtube.com

The Basics of Fgets Function in C Programming Language

Fgets is a function in the C programming language that allows you to read a line from a file. It is a standard library function that is included in the stdio.h header file. The fgets function takes three arguments: the buffer to store the input, the maximum number of characters to read, and the file pointer.

Understanding the Syntax of Fgets Function

The syntax of the fgets function is as follows: ```c char *fgets(char *str, int n, FILE *stream); ``` - str: the buffer to store the input - n: the maximum number of characters to read - stream: the file pointer

Using Fgets Function to Read from a File

To use the fgets function to read from a file, you first need to open the file using the fopen function. The fopen function takes two arguments: the name of the file and the mode in which to open the file. ```c FILE *fptr; char filename[100], c; printf("Enter the filename to open: "); scanf("%s", filename); fptr = fopen(filename, "r"); ``` Once the file is open, you can use the fgets function to read a line from the file. ```c char buffer[100]; while (fgets(buffer, 100, fptr) != NULL) { printf("%s", buffer); } ```

Using Fgets Function to Read from Standard Input

You can also use the fgets function to read from standard input. To read from standard input, you need to pass the stdin file pointer as the third argument to the fgets function. ```c char buffer[100]; printf("Enter a string: "); fgets(buffer, 100, stdin); printf("You entered: %s", buffer); ```

Handling Errors with Fgets Function

The fgets function returns a null pointer if it encounters an error or if it reaches the end of the file. You can use the feof function to check if the end of the file has been reached. ```c char buffer[100]; if (fgets(buffer, 100, fptr) == NULL) { if (feof(fptr)) { printf("End of file reached\n"); } else { printf("Error reading file\n"); } } ```

Conclusion

In conclusion, the fgets function is a useful function in the C programming language that allows you to read a line from a file or standard input. By understanding the syntax and usage of the fgets function, you can easily read data from files and handle errors that may occur.