help in transfoming C++ code into regular ansi C..

the instruction for building this program is not allowing me
to call functions,use iosteam ,use arrays

what they want is just If ,while,for commands , simple variable,only stdio.h
in C

how to transform this code into that??

Code:

---

#include <iostream>

unsigned sum_of_divisors(unsigned n) {
  int result=1;
 
  for(unsigned k=2;k*k<=n;++k) {
    if(n&#37;k==0) {
      int sum_of_powers=1, power=1;
      do {
        power*=k;
        sum_of_powers+=power;
        n/=k;
      } while(n%k==0);
      result*=sum_of_powers;
    }
  }
  return n>1? (n+1)*result : result;
}

bool is_abundant(unsigned n) {
  // The body of this function can be substituted by simply                   
  // return sum_of_divisors(n)>2*n;                                           
  // This is a memoized version.                                             
  const int cache_size=1000000;
  static char cache[cache_size]={0};
  if(n<cache_size && cache[n])
    return cache[n]-1;
  bool result=(sum_of_divisors(n)>2*n);
  if(n<cache_size)
    cache[n] = 1+result;
  return result;
}

void print_if_sum_of_abundants(unsigned n) {
  for(unsigned i=1;i*2<=n;++i) {
    if(is_abundant(i)&&is_abundant(n-i)) {
      std::cout << n << " = " << i << " + " << (n-i) << '\n';
      return;
    }
  }
}

int main() {
  int limit;
  std::cout << "Enter limit: ";
  std::cin >> limit;
 
  for(unsigned i=1;i<=limit;++i)
    print_if_sum_of_abundants(i);
}

---

so where is your attemp to solve the problem?

i changed the iosteam into stdio.h
i wrote unsigned k; outside
and deleted the unsigned in for

but thats as far as my knowledge in c++ goes

replace std::cout << with printf
std::cin >> with scanf
and show the resulting code

still its not running

??

Code:

---

#include <stdio.h>

unsigned sum_of_divisors(unsigned n) {
  int result=1;
unsigned k;
  for(  k=2;k*k<=n;++k) {
    if(n&#37;k==0) {
      int sum_of_powers=1, power=1;
      do {
        power*=k;
        sum_of_powers+=power;
        n/=k;
      } while(n%k==0);
      result*=sum_of_powers;
    }
  }
  return n>1? (n+1)*result : result;
}

bool is_abundant(unsigned n) {
  // The body of this function can be substituted by simply
  // return sum_of_divisors(n)>2*n;
  // This is a memoized version.
  const int cache_size=1000000;
  static char cache[cache_size]={0};
  if(n<cache_size && cache[n])
    return cache[n]-1;
  bool result=(sum_of_divisors(n)>2*n);
  if(n<cache_size)
    cache[n] = 1+result;
  return result;
}

void print_if_sum_of_abundants(unsigned n) {
  unsigned i;
  for(i=1;i*2<=n;++i) {
    if(is_abundant(i)&&is_abundant(n-i)) {
        printf("%d=%d+%d\n",n,i,n-i);

      return;
    }
  }
}

int main() {
  int limit;
  printf(" "Enter limit: ");
  scanf("%d",&limit);
unsigned i;
  for(i=1;i<=limit;++i)
    print_if_sum_of_abundants(i);
}

---

What does not running mean?

i get these syntax errors from the compilers:
C:\Documents and Settings\lun\My Documents\ass1\ass1.c|20|error: syntax error before "is_abundant"|
C:\Documents and Settings\lun\My Documents\ass1\ass1.c|20|warning: return type defaults to `int'|
C:\Documents and Settings\lun\My Documents\ass1\ass1.c||In function `is_abundant':|
C:\Documents and Settings\lun\My Documents\ass1\ass1.c|25|error: variable-sized object may not be initialized|
C:\Documents and Settings\lun\My Documents\ass1\ass1.c|25|warning: excess elements in array initializer|
C:\Documents and Settings\lun\My Documents\ass1\ass1.c|25|warning: (near initialization for `cache')|
C:\Documents and Settings\lun\My Documents\ass1\ass1.c|25|error: storage size of 'cache' isn't constant|
C:\Documents and Settings\lun\My Documents\ass1\ass1.c|28|error: `bool' undeclared (first use in this function)|
C:\Documents and Settings\lun\My Documents\ass1\ass1.c|28|error: (Each undeclared identifier is reported only once|
C:\Documents and Settings\lun\My Documents\ass1\ass1.c|28|error: for each function it appears in.)|
C:\Documents and Settings\lun\My Documents\ass1\ass1.c|28|error: syntax error before "result"|
C:\Documents and Settings\lun\My Documents\ass1\ass1.c|30|error: `result' undeclared (first use in this function)|
C:\Documents and Settings\lun\My Documents\ass1\ass1.c|25|error: size of variable 'cache' is too large|
C:\Documents and Settings\lun\My Documents\ass1\ass1.c||In function `main':|
C:\Documents and Settings\lun\My Documents\ass1\ass1.c|47|error: syntax error before "Enter"|
C:\Documents and Settings\lun\My Documents\ass1\ass1.c|47|error: missing terminating " character|
||=== Build finished: 11 errors, 3 warnings ===|

Firstly, can you use / are you using C99?
And secondly, this has little to do with C++ anymore - mostly syntax errors, undeclared identifiers and variables not defined at the start of a block.

i am using codeblocks8.02 compiler
i dont know if its using C99

i got a function is_abundant(unsigned n) defined as bool

i know thats its not possible in C
and

C:\Documents and Settings\lun\My Documents\ass1\ass1.c|25|error: storage size of 'cache' isn't constant|

??

and how to interpret this line :

return n>1? (n+1)*result : result;

Quote:

---

Originally Posted by transgalactic2

i am using codeblocks8.02 compiler
i dont know if its using C99

---

Code::Blocks is not a compiler; it's an IDE.

Quote:

---

i got a function is_abundant(unsigned n) defined as bool

i know thats its not possible in C

---

It's possible in C99.
Otherwise just typedef it.

Quote:

---

and

C:\Documents and Settings\lun\My Documents\ass1\ass1.c|25|error: storage size of 'cache' isn't constant|

??

---

Make:

Code:

---

        const int cache_size=1000000;
        static char cache[cache_size]={0};

---

Into:

Code:

---

        static char cache[1000000]={0};

---

C++ can take constants that can be evaluated at compile time to specify the size of an array, while C cannot.

Quote:

---

Originally Posted by transgalactic2

and how to interpret this line :

return n>1? (n+1)*result : result;

---

Code:

---

if (n > 1)
    return (n + 1) * result;
else
    return result;

---

i did the changes you told

i cant use bool type
and
i am not allowed to use typedef on the bool problem

how to replace it with intege variables of 1 and 0??

i get a bug that cache_size is not defined in is_abundant(unsigned n)

C:\Documents and Settings\lun\My Documents\ass1\ass1.c|30|error: `cache_size' undeclared (first use in this function)|

i dont know how to define cache_size

i cant use type unsigned only integer/long integer
how to replace it??

Code:

---

#include <stdio.h>

unsigned sum_of_divisors(unsigned n) {
  int result=1;
unsigned k;
  for(  k=2;k*k<=n;++k) {
    if(n&#37;k==0) {
      int sum_of_powers=1, power=1;
      do {
        power*=k;
        sum_of_powers+=power;
        n/=k;
      } while(n%k==0);
      result*=sum_of_powers;
    }
  }
  if (n > 1)
    return (n + 1) * result;
else
    return result;
}

int is_abundant(unsigned n) {

  // The body of this function can be substituted by simply
  // return sum_of_divisors(n)>2*n;
  // This is a memoized version.
  static char cache[1000000]={0};

  if(n<cache_size && cache[n])
    return cache[n]-1;
  bool result=(sum_of_divisors(n)>2*n);
  if(n<cache_size)
    cache[n] = 1+result;
  return result;
}

void print_if_sum_of_abundants(unsigned n) {
  unsigned i;
  for(i=1;i*2<=n;++i) {
    if(is_abundant(i)&&is_abundant(n-i)) {
        printf("%d=%d+%d\n",n,i,n-i);

      return;
    }
  }
}

int main() {
  int limit;
  printf(" "Enter limit: ");
  scanf("%d",&limit);
unsigned i;
  for(i=1;i<=limit;++i)
    print_if_sum_of_abundants(i);
}

---

Quote:

---

Originally Posted by transgalactic2

i cant use bool type
and
i am not allowed to use typedef on the bool problem

---

...And why not?

Quote:

---

how to replace it with intege variables of 1 and 0??

---

You can't. But you can use an integer or whatever that can holds values more than 0 and 1. It works, as well, but not limited to only 1 and 0.

Quote:

---

i get a bug that cache_size is not defined in is_abundant(unsigned n)

C:\Documents and Settings\lun\My Documents\ass1\ass1.c|30|error: `cache_size' undeclared (first use in this function)|

---

Sigh, so make a define!

Quote:

---

i cant use type unsigned only integer/long integer
how to replace it??

---

Unless you use C99, no.

i am restricted to these simple commands
because we havent studied them in the course

i cant use define


i can use visual studio 2005
but only a simple commands

So hard-code them, then.
If you haven't studied them in a course, then why are you trying to change C++ code that contains these things into C code?

Because this c++ code is a complete solution to my problem .
Unfortunately i cant see the logic of it.
and there are too many commands which are needed to be replaced.

and i now very little c++.

And now you have erased everything C++, and all that's left is C. Yet you still struggle.
I'm just saying - I don't think this is a good idea!
If you have an assignment, why should you hunt for solutions when you should write the code yourself?

Quote:

---

Originally Posted by transgalactic2

Because this c++ code is a complete solution to my problem .
Unfortunately i cant see the logic of it.

---

So, you happened to find this C++ program somewhere, and basically want to copy it, but you have to hand in a C program compilable under C90.

Clearly, your assignment is not about transforming a C++ program into a C program, which was what I thought you were trying to do. I believe others who contributed to this thread thought the same. Rather, the aim was for you to develop a solution to the problem and implement it in C.

What you should be asking for is help in understanding the solution that you have found so that you can re-implement it in C. Mechanically translating the solution from C++ to C is tantamount to plagarism, and arguably as bad as finding a solution in C and handing it up as your own work. You may even be guilty of copyright infringement if you do not have permission to copy and make a derivative work.

It was written in c++ specifically for my problem.
I did not steal it.
I have built some thing close.

But it gives me the right a right pair numbers many times .
for input 54 it gives me 12 42 12 42 12 42 (it should give me only one pair) 12 42
and it doesnt give me the result for 53 52 .. 1
(whether they are a sum of two abounded numbers)

i tried to trace with a debugger but i cant see the problem
??

Code:

---




#include <stdio.h>


 //////////////////////////////////////////////////////////////00000000

int  main(){
    int num;
    int index,tndex,kndex,jndex;
    int flag_1,flag_2,same_num;
    int sum;
    int smallest,smallest_ever,smallest_ever_2;
    sum=0;
    same_num=-1;

    smallest=-1;

    printf("enter number\n");
    scanf("&#37;d",&num);

    for(index=1;index<num;index++){ //start for main number
        flag_1=0;

        sum=0;
    flag_2=0;

        tndex=index;
            kndex=num-tndex;


                      sum=0;
                    for(jndex=1;jndex<tndex;jndex++){//start abbondence check for first num (tndex)
                        if (tndex%jndex==0){
                            sum=sum+jndex;
                        }
                        if (tndex<sum){
                        flag_1=1;
                    }

                    }//end abbondence check for first num


                    sum=0;
                    for(jndex=1;jndex<kndex;jndex++){//start abbondence check for second num (kndex)
                        if (kndex%jndex==0){
                            sum=sum+jndex;
                        }
                    if (kndex<sum){
                        flag_2=1;
                    }

                    }//end abbondence check for first num

                    if ((flag_2==1)&&(flag_1==1)){  //start flag check
                        if (kndex>=tndex){
                            smallest=tndex;

                            if ((smallest<smallest_ever)&&(smallest>1)){
                                smallest_ever=smallest;
                                smallest_ever_2=kndex;
                            }
                        }
                        else
                        {
                            smallest=kndex;
                            if ((smallest<smallest_ever)&&(smallest>1)){
                                smallest_ever=smallest;
                                smallest_ever_2=tndex;
                            }
                        }

                        printf("%d %d\n",smallest_ever,smallest_ever_2);
                        }

                    }//end flag check









  return 0;
}//end main

---