Category Archives: C Basic I/O

Basic input output programs in C.

C code to hide input password

C program to hide input password with *
In this code Password accepts all character except ‘\n’ .

password

 

 

 

char input in c using scanf

Char input in c using format specifier %c in scanf.

 

 

 

 

Float input in C using %f

Here is the code to take a floating point value as input and print the same.

scanf is the function used to take input from standard input , where %f is the format identifier for the floating point value.

Float input in C

 

Float input in C . Integer input in C

Input integer array in C

String is also an array of char but we have functions to take input string . For inputting the int array ,float array we dont have functions like string. Here is the code for inputting integer array , similarly we can apply it for float too.

Example :

 

 

String input in C using gets

The problem with scanf function is it doesnot recognises space in Name. Exmple if you entered string as “Coding street” it will store only coding in string variable so it is recommended by us to use gets over string input. Because it recognizes space and takes space also as input.

Example :

 

Input basic Data types (int, float, char)

Below program takes input of integer, float, string value from keyboard and prints it on screen.

 

C File Handling

File handling in c means we can create,open , delete files and modify contents in file.For this operations we will use some file handling functions. fopen, fclose, fscanf, fprintf ,fgets, fputs, feof etc.

File operations follow this procedure :

name of file

open or create file

read or write on file.

close file


File Handling Modes :

File Mode

Description

r

Opens a file in read only mode.

w

Opens a file in write mode , it creates a new file with provided file name if it doesnot exist.If file exists then file will be overwritten.

a

Opens a file in append mode ( new info will be added at end of file), If file doesnot exist then it will create a new file.

r+

Opens a file for read and write mode.

w+

Opens a file for read and write mode.It creates a new file if it doesnot exist.

a+

Opens a file for read and write mode. It create a new file if it doesnot exist.

rb

Opens a binary file for reading.

wb

Opens a binary file for writing.If file exist it will be over written.

ab

Opens a binary file in append mode.Info is added at end of file.

r+b or rb+

Opens binary file for reading and writing

w+b or wb+

Opens a binary file for read and write mode.It creates a new file if it doesnot exist.

a+b or ab+

Opens a binary file for read and write mode. It create a new file if it doesnot exist.

File handling functions :

fopen : To open or create file

fclose : To close a open file, we need file pointer of opened file.

Where fp is  file pointer.

fscanf : To read from file according to format provided.

fprintf : To write into file according to format provided.

feof : To check end of file.

 fgets : Reads a line from file and stores in string.

fputs: Writes a string into file.

 fgetc: Reads a single character from file into char variable.

 fputc: Writes a single character to file.

 Example :

Program to copy content of one file into other file.

Given:

Source filename :src.txt

Destination filename: dst.txt

Explanation :

Above code copies content of one txt file into other txt file.

sfp  & dfp are file pointers.

src file is opened in read mode and dst file is is opened in write mode.

We will stop copying content when source file(src.txt) file pointer reaches to EOF (EOF is end of file which indicates that we have reached at end of file ).

we are using fgetc function to get char from src file. We are storing fetched content from source file into character variable c, then we are storing back the value of character variable c into the destination file using fputc function.

After copying the content we are closing the opened files.