Convert code C to C#

Question

Help me convert this code is in C language to C #

#include<stdio.h> 
#include<conio.h> 
#include<stdlib.h> 
#include<math.h> 
#include<string.h> 

long int p,q,n,t,flag,e[100],d[100],temp[100],j,m[100],en[100],i; 
char msg[100]; 
int prime(long int); 
void ce(); 
long int cd(long int); 
void encrypt(); 
void decrypt(); 
void main() 
{ 
clrscr(); 
printf("\nENTER FIRST PRIME NUMBER\n"); 
scanf("%d",&p); 
flag=prime(p); 
if(flag==0) 
{ 
    printf("\nWRONG INPUT\n"); 
    getch(); 
    exit(1); 
} 
printf("\nENTER ANOTHER PRIME NUMBER\n"); 
scanf("%d",&q); 
flag=prime(q); 
if(flag==0||p==q) 
{ 
    printf("\nWRONG INPUT\n"); 
    getch(); 
    exit(1); 
} 
printf("\nENTER MESSAGE\n"); 
fflush(stdin); 
scanf("%s",msg); 
for(i=0;msg[i]!=NULL;i++) 
m[i]=msg[i]; 
n=p*q; 
t=(p-1)*(q-1); 
ce(); 
printf("\nPOSSIBLE VALUES OF e AND d ARE\n"); 
for(i=0;i<j-1;i++) 
printf("\n%ld\t%ld",e[i],d[i]); 
encrypt(); 
decrypt(); 
getch(); 
} 
int prime(long int pr) 
{ 
int i; 
j=sqrt(pr); 
for(i=2;i<=j;i++) 
{ 
    if(pr%i==0) 
    return 0; 
} 
return 1; 
} 
void ce() 
{ 
int k; 
k=0; 
for(i=2;i<t;i++) 
{ 
    if(t%i==0) 
    continue; 
    flag=prime(i); 
    if(flag==1&&i!=p&&i!=q) 
    { 
        e[k]=i; 
        flag=cd(e[k]); 
        if(flag>0) 
        { 
            d[k]=flag; 
            k++; 
        } 
        if(k==99) 
        break; 
    } 
} 
} 
long int cd(long int x) 
{ 
long int k=1; 
while(1) 
{ 
    k=k+t; 
    if(k%x==0) 
    return(k/x); 
} 
} 
void encrypt() 
{ 
long int pt,ct,key=e[0],k,len; 
i=0; 
len=strlen(msg); 
while(i!=len) 
{ 
    pt=m[i]; 
    pt=pt-96; 
    k=1; 
    for(j=0;j<key;j++) 
    { 
        k=k*pt; 
        k=k%n; 
    } 
    temp[i]=k; 
    ct=k+96; 
    en[i]=ct; 
    i++; 
} 
en[i]=-1; 
printf("\nTHE ENCRYPTED MESSAGE IS\n"); 
for(i=0;en[i]!=-1;i++) 
printf("%c",en[i]); 
} 
void decrypt() 
{ 
long int pt,ct,key=d[0],k; 
i=0; 
while(en[i]!=-1) 
{ 
    ct=temp[i]; 
    k=1; 
    for(j=0;j<key;j++) 
    { 
        k=k*ct; 
        k=k%n; 
    } 
    pt=k+96; 
    m[i]=pt; 
    i++; 
} 
m[i]=-1; 
printf("\nTHE DECRYPTED MESSAGE IS\n"); 
for(i=0;m[i]!=-1;i++) 
printf("%c",m[i]); 
}

This code is an implementation of  RSA encryption.

Thanks in advance

Answer 1

Help me convert this code is in C language to C #

long int p,q,n,t,flag,e[100],d[100],temp[100],j,m[100],en[100],i;

void main() 
{ 
clrscr(); 

...

} 

int prime(long int pr) 
{ 
int i; 
j=sqrt(pr); 

...

}

This code is an implementation of  RSA encryption.

Is there any good reason why you are trying to convert this C program?

Note that it doesn't appear to have been written for Visual C/C++, as clrscr()
has never been available in VC++. It is mostly found in the former
Borland/Turbo C++ compilers. Also the sqrt() function in VC++ expects a float
or double as an argument, not a long, and it returns a double not a long.

For C# you should be looking at what is already available for doing RSA encryption.

For example:

RSA Class
https://msdn.microsoft.com/en-us/library/system.security.cryptography.rsa(v=vs.110).aspx

- Wayne

Answer 2

As has already been reported to clrscr, some statements have no equivalent in C#.
You can also remove fflush (stdin);

If you create a C# application in console mode:

printf may be replaced by Console.WriteLine

and scanf by Console.ReadLine

long int by long

len = strlen (msg); by len = msg.Length;

etc.

Answer 3

Hi Vando1258,

Thank you for posting here.

For your question, you could use tools to convert C++ TO C#.

Note: This response contains a reference to a third party World Wide Web site. Microsoft is providing this information as a convenience to you. Microsoft does not control these sites and has not tested any software or information found on these sites; Therefore, Microsoft cannot make any representations regarding the quality, safety, or suitability of any software or information found there.

I hope this would be helpful to you.

Best Regards,

Wendy

---

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