Write a program in C to merge two files and write it in a new file. When we open the file in âread modeâ, the file is first searched for in the disk and then loaded into the buffer. :: The lines are :: Test Data : Input the number of lines to be ⦠Input the name of file to delete : test.txt close(): To close an existing file. test line 7 Write a program in C to decrypt a previously encrypted file file. Write a program in C to find the content of the file and number of lines in a Text File. For opening a text file; Start; Declare variable and file pointer; Assign file pointer to fopen() function with write format; If file is not opened, print error message; Else give the content using loop; Close the file; Stop; For Reading a Text File I am trying to write "File opened" in a existing test.txt file with C program. C Program Input/output with files C++ provides the following classes to perform output and input of characters to/from files: ofstream: Stream class to write on files; ifstream: Stream class to read from files; fstream: Stream class to both read and write from/to files. Test Data : Go to the editor. Writes a single character to a file. In simplest words, we can say that in order to read data from a file we use ifstream class. You can find all the code examples and the input file at the GitHub repo for this article. Test Data : Expected Output : 2. Go to the editor. Test Data : "); // Program exits if the file pointer returns NULL. Input the file name to be opened : test.txt After this reading and writing, we will close both files. General functions used for File handling. write (): It is used to write data into a file. Go to the editor. Definition of C++ Read File. The main advantage to a #define is that it requires no memory to store in your program, as it is really just replacing some text with a literal value. But I must not create a test.txt file with the program. Input the content of the new line : Yes, I am the new text instead of test line 2 In order to read information from a file, or to write information to a file, your program must take the following actions. Home » Solved C++ Programs » C++ File Handling Programs C++ program to write and read text in/from file In this program, we will create a file and then write some text into then file , after writing text file will be closed and again file will open in read mode, read all written text. Create a new file and write to it. Input the name of file to decrypt : test.txt The Read a text file section of this article describes how to use the StreamReader class to read a text file. Input the file name to be opened : test.txt Input the new file name : test1.txt Let's say you have prepared your final project report. A stream is an abstraction that represents a device on which operations of input and output are performed. Now, we will read the contents of the file and then print those on the screen. test line 5 C Program to Read content of a File and Display it Below is a simple program to read the content of any file and then print it on the output screen. close (): It is used to close an existing file. Allow both read and write operations to this file. Go to the editor If the file opening is successful, then it returns a pointer to the file, and if it's unable to open it, then it returns NULL. test line 3 Write a program in C to replace a specific line with another text in a file. . However, instead of using the cin object, you use the ifstream/ fstream object. for each element, fgetc is called size times (count of bytes for a single element) and file position indicator for the stream is advanced by the number of characters read. Reading from a file â The file read operations can be performed using functions fscanf or fgets. Input the line no you want to replace : 2 Now, we will read a source file character by character and at the same time, we will write this character into the destination file. Input the 2nd file name : test1.txt Scala Programming Exercises, Practice, Solution. Write a program in C to create and store information in a text file. Write a program in C to delete a specific line from a file. Syntax in C language size_t read (int fd, void* buf, size_t cnt); Input the file name to be opened : test.txt Write a program in C to write multiple lines in a text file. Go to the editor C program to copy contents from one file to another file. Input the file name to be opened : test.txt You can read information from files into your C++ program. Go to the editor Previous: Write a program in C to create and store information in a text file. Expected Output : 9. opening file"); // exit from program if file pointer returns NULL. open(): To create a file. #include #include // for exit() function int main() { char c[1000]; FILE *fptr; if ((fptr = fopen("studytonight.txt", "r")) == NULL) { printf("Error! Go to the editor The fread function generally used for binary file to read the binary data from the given file stream. test line 2 Expected Output : Do not submit any solution of the above exercises at here, if you want to contribute go to the appropriate exercise page. Expected Output : 3. Test Data : Both the functions performed the same operations as that of scanf and gets but with an additional parameter, the file pointer. Write a program in C to Find the Number of Lines in a Text File. Classes for Reading/Writing Files In C++, three major files are used for interacting with files. Write the file. Write a program in C to read an existing file. C program to compare two files. Input the number of lines to be written : 3 The main advantage to a #define is that it requires no memory to store in your program, as it is really just replacing some text with a literal value. Expected Output : 10. Have another way to solve this solution? getw () Reads an integer from a file. Write a program in C to read the file and store the lines into an array. The Write a text file (example 1) and the Write a text file (example 2) sections describe how to use the StreamWriter class to write text to a file. Close the file. The lines are : Input the filen ame to be opened : test.txt #include #include void main() { FILE *fptr; char fname[20]; char str; printf("\n\n Read an existing file :\n"); printf("-----\n"); printf(" Input the filename to be opened : "); scanf("%s",fname); fptr = fopen (fname, "r"); if (fptr == NULL) { printf(" File does not exist or cannot be opened.\n"); exit(0); } printf("\n The content of the file %s is :\n",fname); str = fgetc(fptr); while (str != ⦠. Go to the editor. This class extracts the contents from the file. read (): It is used to read data from a file. Expected Output : 4. Test Data : Test Data : Expected Output : 7. Write a program in C to encrypt a text file. Test Data : ⦠test line 1 Input the name of file to encrypt : test.txt C program to read and merge two files in single file. Is it better to use static const vars than #define preprocessor? struct food { int no; string name; float cost; }s; //TO read from file void read () { fstream f; f.open ("Existingfile.txt",ios::in); while (!f.eof ()) { f.read ( (char*)&s,sizeof (s)); . Test Data : Input a sentence for the file : This is the content of the file test.txt. This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. Advantages of "const"s are that they can be scoped, and they can be used in situations where a pointer to an object needs to be passed. 1. fstream ifstream (Input Stream) is a class that is used to obtain input from any file. Go to the editor It is declared in stdio.h and takes four arguments. Test Data : Write a program in C to write multiple lines in a text file. If my question is not correct, please comment and I will clear it. f.close (); } P.S: I am new to stackoverflow. This is possible using stream extraction operator (>>). put (): It is used to write a single character in the file. Test Data : Now see this program to copy one file ⦠#include #include // For exit () function int main() { char c [1000]; FILE *fptr; if ( (fptr = fopen ("program.txt", "r")) == NULL) { printf("Error! We open the file in ârâ or read mode which allows us to read the contents of the file. Go to the editor. Reading from a File; Close a File; File Handling In C++. Expected Output : 6. Input the file name to be opened : test.txt Go to the editor A successful read () updates the access time for the file. Write a program in C to count a number of words and characters in a file. Function fopen is used to open a file; it returns a pointer to structure FILE, which is a predefined structure in the "stdio.h" header file. As we are well aware that C++ is one of the most widely used languages and it provides many features that allows the programmer to perform multiple tasks easily. Reading Files in C Program. Write a C program to read name and marks of n number of students from user and store them in a file. C program to read a file and print its content. exit(1); } // reads text until newline is encountered fscanf(fptr, "% [^\n]", c); printf("Data from the file:\n%s", c); fclose (fptr); return 0; } After that, fscanf function will read the contents of the file and printf function will display the contents of the file on the screen. The algorithm for opening and reading a text file in C has given below: Algorithm for Opening and Reading the text file. Expected Output : Now, if you read the file test.txt you will see the following : 15. Input the line you want to remove : 2 Go to the editor Test Data : C program to read a file and display its contents - Codeforwin Write a program in C to copy a file in another name. open (): It is used to create and open a file. Expected Output : 11. Input the file name to be opened : test.txt Files are used to store data in a storage device permanently. Expected Output : If you read the file test.txt you will see the following : 14. In C, we use a structure pointer of a file type to declare a file: FILE *fp; C provides a number of build-in function to perform basic file operations: fopen() - create a new file or open a existing file; fclose() - close a file; getc() - reads a character from a file Go to the editor âr+â Open an existing file. Before reading the file using programming, just create a text file in the current directory and add some text in a file using simple notepad. . If the file previously exits, add the information of n students. read: From the file indicated by the file descriptor fd, the read () function reads cnt bytes of input into the memory area indicated by buf. Test Data : 2. ofstream If the file does not exist, create a new one and write to it. Expected Output : Here is the content of the merge file mergefiles.txt : 13. Contribute your code (and comments) through Disqus. . } Expected Output : 8. Program to read the first line from a file. Input the source file name : test.txt Next: Write a program in C to write multiple lines in a text file. Input the file name to be opened : test.txt ftell () Returns the current position of a file pointer. You use the operator in the same way you use it to read user input from the keyboard. It also has the advantage that it has no type, so it can be used for any integer value without generating warnings. In order to read or write to a file, we must first open the file using the function fopen (). How to Read/ Write (I/O) Strings in Files â fgets & fputs Follow the steps to read the file: Create a file pointer. The report spans across numerous File handling provides a mechanism to store the output of a program in a file and to perform various operations on it. File handling is one of the most important parts of programming. What is the difficulty level of this exercise? Test Data : test line 6 Expected Output : If you read the new file you will see the content of the file : 12. File cannot be opened. 1) Create a variable to represent the file. Test Data : a file with content that is opened by another process for reading; a file with content that is opened by another process for writing 1. fseek () Sets the position of a file pointer to a specified location. Input the number of lines to be written : 4 Write a program in C to read an existing file. Input the new file name where to merge the above two files : mergefiles.txt âaâ Append to the end of a file. test line 4 In C++, working on file operations is as easy as working normally on ⦠Also read: Program in C to Replace Capital C with Capital S in a File. putw () Writing an integer to a file. It also has the advantage that it has no type, so it can be used for any integer value without generating warnings. Write a program in C to append multiple lines at the end of a text file. Test Data : 2) Open the file and store this "file" with the file variable. Go to the editor. Input the 1st file name : test.txt Expected Output : 5. Reading a file line by line is a trivial problem in many programming languages, but not in C. The standard way of reading a line of text in C is to use the fgets function, which is fine if you know in advance how long a line of text could be. Scala Programming Exercises, Practice, Solution. For that, we will first open the file in read mode using fopen function. get (): It is used to read a single character from the file. I have to write with in a existing file⦠File Input and Output in C . Read a text file. C program to create a file and write data into file. The function fscanf () permits to read and parse data from a file We can read (using the getc function) an entire file by looping to cover all the file until the EOF is encountered We can write to a file after creating its name, by using the function fprintf () and it must have the newline character at the end of the string text. Advantages of "const"s are that they can be scoped, and they can be used in situations where a pointer to an object needs to be passed. If a file with the same name already exists, overwrite it â rather, erase the existing file and create a new one. Write a program in C to remove a file from the disk. This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. Is it better to use static const vars than #define preprocessor? an existing file with the last line not terminated by a newline character (could be considered being an invalid file format, since lines mostly are considered to be newline-terminated, not newline-separated). . Go to the editor.