How to Get Time and Date in C - C Program to Read and Display Time and Date

In this post, we will discuss how to read system time (current time) and date in c. To get system time and date, we use the time.h header file. It contains functions related to time and date. The function time() reads the current time and stores in the variable given as parameter. For example, if we call time(now), then the variable now is assigned the current date and time value. This parameter should be of type time_t. A sample code is:

time_t now;
time ( &now );

Note that we should pass the reference to a variable of type time_t.  But, the value stored by the function time() contains all information including date and time. So, the value appears to be an unintelligible random number. There fore, to extract hours, minutes, seconds, year, month, day of month etc from this value, we should convert into an object of structure struct tm. The function localtime() converts the value for us. This conversion to date and time can be done as follows:

C Program to open, read and write files and perform file copy operation usingSystem Calls in UNIX

Write a program to open, read and write files and perform file copy operation. This program show how to open, read, write and copy files using Linux or Unix system calls like open(), read() and write().

#include<stdio.h>
#include<fcntl.h>
main()
{


char buff[1000],fn1[10],fn2[10];
int fd1,fd2,n;
printf("Enter source filename\n");
scanf("%s",fn1);
printf("Enter destination file name\n");
scanf("%s",fn2);
fd1=open(fn1,O_RDONLY);
n=read(fd1,buff,1000);
fd2=open(fn2,O_CREAT|O_WRONLY);
n=write(fd2,buff,n);
close(fd1);
close(fd2);
}

C Program to Open, Read and Write a file using System Calls

This is a C program to open , read and write files using system calls in Linux (UNIX) operating systems. The system calls open(), read() and write() are used in the C program to open, read and write files in Unix/Linux operating systems.

#include<stdio.h>
#include<fcntl.h>
main()
{


char buff[100],fn[10];
int fd,n;
printf("Enter file name\n");
scanf("%s",fn);
fd=open(fn,O_RDONLY);
n=read(fd,buff,100);
n=write(1,buff,n);
close(fd);
}