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?