Notes

1)FILE OPERATORS
1)write data 2)read & display contents 3)append

#include <stdio.h>
#include <stdlib.h>
int main()
{
int num; FILE *fptr;
fptr = fopen("program.txt","w");
if(fptr == NULL)
{
printf("Error!");
exit(1);
}
printf("Enter number to be added to file: n");
scanf("%d",&num);
fprintf(fptr,"%d",num);
fclose(fptr);

if ((fptr = fopen("program.txt","r")) == NULL)
{
printf("Error! opening file");
exit(1);
}
fscanf(fptr,"%d", &num);
printf("Values on the file are n=%dn", num);
fclose(fptr);

fptr = fopen("program.txt","a");
if(fptr == NULL)
{
printf("Error!");
exit(1);
}
printf("Enter number to be appended to file : ");
scanf("%d",&num);
fprintf(fptr,"%d",num);
fclose(fptr);

if ((fptr = fopen("program.txt","r")) == NULL)
{
printf("Error! opening file");
exit(1);
}
fscanf(fptr,"%d", &num);
printf("Values on the file are n=%dn", num);
fclose(fptr);
return 0;
}


2)OPEN TEXT INPUT
COUNT CHARECTERS , WORDS , LINES & STORE OUTPUT

#include <stdio.h>
#include <stdlib.h>
int main()
{
FILE * file; char ch;
int characters, words, lines;
file = fopen("text1.txt","r");
if (file == NULL)
{
printf("nUnable to open file.n");
printf("Please check if file exists and you have read privilege.n");
exit(EXIT_FAILURE);
}
characters = words = lines = 0;
while ((ch = fgetc(file)) != EOF)
{
characters++;
if (ch == 'n' || ch == '')
lines++;
if (ch == ' ' || ch == 't' || ch == 'n' || ch == '')
words++;
}
if (characters > 0)
{
words++;
lines++;
}
printf("n");
printf("Total characters = %dn", characters);
printf("Total words= %dn", words);
printf("Total lines= %dn", lines);
fclose(file);
return 0;
}



String reverse using function


#include <stdio.h>
void stringreverse(char* s)
{
char r[100];
int begin, end, count = 0;
printf("Input a stringn");
scanf("%s",s);
while (s[count] != '')
count++;
end = count - 1;
for (begin = 0; begin < count; begin++)
{
r[begin] = s[end];
end--;
}
r[begin] = '';
printf("Reverse of entered string is %sn", r);
}
void main()
{
char s[100];
stringreverse(s);
}





Factorial of a number using loop




#include<stdio.h>
int main()
{
int num, i, fact = 1;
printf("Enter a number to find factorialn");
scanf("%d", &num);
for(i = 1; i <= num; i++)
{
fact = fact * i;
}
printf("Factorial of %d is %dn", num, fact);
return 0;
}

8) EMPLOYEE DETAILS

#include <stdio.h>
struct employee
{
char name[30];
int empid;
float salary;
};
void main ()
{
struct employee emp;
printf("nEnter details:n");
printf("Enter name:");
scanf("%s",emp.name);
printf("enetr ID:");
scanf("%d",&emp.empid);
printf("Enter salary:");
scanf("%f",&emp.salary);
printf("nEntered details is:n");
printf("Name:%sn",emp.name);
printf("ID:%dn",emp.empid);
printf("Salary:%fn",emp.salary);
}


9) PERSONAL DETAILS USING UNION

#include <stdio.h>
#include <string.h>
#define C_SIZE 20
union test
{
char name[C_SIZE];
char house[C_SIZE];
char city[C_SIZE];
char state[C_SIZE];
char pincode[C_SIZE];
};
void main()
{
union test t;
printf("Enter the name of person :n");
scanf("%s",t.name);
printf("The name of the person is : n");
puts(t.name);
printf("Enter the house name of person :n");
scanf("%s",t.house);
printf("The house of the person is : n");
puts(t.house);
printf("Enter the city of person :n");
scanf("%s",t.city);
printf("The city of the person is : n");
puts(t.city);
printf("Enter the state of person :n");
scanf("%s",t.state);
printf("The state of the person is : n");
puts(t.state);
printf("Enter the pincode of person :n");
scanf("%s",t.pincode);
printf("The pincode of the person is : n");
puts(t.pincode);
}

10) StRING REVERSE

#include <stdio.h>
void stringreverse(char* s)
{
char r[100];
int begin, end, count = 0;
printf("Input a stringn:n");
scanf("%s",s);
while (s[count] != '')
count++;
end = count - 1;
for (begin = 0; begin < count; begin++)
{
r[begin] = s[end];
end--;
}
r[begin] = '';
printf("Reverse of entered string is %sn",r);
}
void main()
{
char s[100];
stringreverse(s);
}

11) FACTORIAL OF NUMBER USING LOOP

#include <stdio.h>
int main()
{
int num, i, fact = 1;
printf("Enter a number to find factorialn");
scanf("%d",&num);
for(i = 1; i <= num; i++)
{
fact = fact * i;
}
printf("Factorial of %d is %dn", num, fact);
return 0;
}


1)SUM USING POINTERS

#include <stdio.h>
int main ()
{
int array [5], i, n, sum = 0,*ptr;
printf (" Enter the number of elements in the array:n");
scanf("%d",&n);
printf ("Enter array elements :n");
for ( i = 0; i<n; i++)
scanf ( "%d",& array [i]);
ptr = array;
for(i=0;i<n;i++)
{
sum=sum+*ptr;
ptr++;
}
printf("the sum is :%d",sum);
return 0;
}