C Exercises: Decrypt a previously encrypted file
C File Handling : Exercise-14 with Solution
Write a program in C to decrypt a previously encrypted file.
Assume that, the content of the file test.txt was : ������Ʉ�ӄۗ�������ɒ��ђn
Sample Solution:
C Code:
#include <stdio.h>
#include <stdlib.h>
void main()
{
char ch, fname[20];
FILE *fpts, *fptt;
printf("\n\n Decrypt a text file :\n");
printf("--------------------------\n");
printf(" Input the name of file to decrypt : ");
scanf("%s",fname);
fpts=fopen(fname, "w");
if(fpts==NULL)
{
printf(" File does not exists or error in opening..!!");
exit(7);
}
fptt=fopen("temp.txt", "r");
if(fptt==NULL)
{
printf(" File does not exists or error in opening..!!");
fclose(fpts);
exit(9);
}
while(1)
{
ch=fgetc(fptt);
if(ch==EOF)
{
break;
}
else
{
ch=ch-100;
fputc(ch, fpts);
}
}
printf(" The file %s decrypted successfully..!!\n\n",fname);
fclose(fpts);
fclose(fptt);
}
Sample Output:
Decrypt a text file : -------------------------- Input the name of file to decrypt : test.txt The file test.txt decrypted successfully..!!
After decrypt, the content of the file is : Welcome to w3resource.com.
Flowchart:

C Programming Code Editor:
Have another way to solve this solution? Contribute your code (and comments) through Disqus.
Previous: Write a program in C to encrypt a text file.
Next: Write a program in C to remove a file from the disk.
What is the difficulty level of this exercise?
Test your Programming skills with w3resource's quiz.
C Programming: Tips of the Day
What is the size of an enum in c?
An enum is only guaranteed to be large enough to hold int values. The compiler is free to choose the actual type used based on the enumeration constants defined so it can choose a smaller type if it can represent the values you define. If you need enumeration constants that don't fit into an int you will need to use compiler-specific extensions to do so.
Ref : https://bit.ly/3ypg4k8
- New Content published on w3resource:
- HTML-CSS Practical: Exercises, Practice, Solution
- Java Regular Expression: Exercises, Practice, Solution
- Scala Programming Exercises, Practice, Solution
- Python Itertools exercises
- Python Numpy exercises
- Python GeoPy Package exercises
- Python Pandas exercises
- Python nltk exercises
- Python BeautifulSoup exercises
- Form Template
- Composer - PHP Package Manager
- PHPUnit - PHP Testing
- Laravel - PHP Framework
- Angular - JavaScript Framework
- Vue - JavaScript Framework
- Jest - JavaScript Testing Framework