Question

Hey everyone, I need help making a function with this directions with C++ Language.

Can you guys use code like printf and fscanf without iostream or fstream because i havent study that yet.

Thanks.

Directions: Write a function declaration and definition for the char* function allocCat. This function should take in as a parameter a const Words pointer (Words is a defined struct) The function should allocate exactly enough memory for the concatenation of all of the strings in the array passed in, then copy those strings, one after the other, into the newly allocated space. The original strings must remain unchanged. The function should return the pointer to the newly allocated space or a NULL pointer if no space was allocated The code below shows an example of how this function might be called. struct words int numberofWords; char theWords [ARRAY_SIZE] [FILENAME MAX]; typedef struct words Words; // alloccat prototype (declaration) goes here: // sample main shows how allocCat might be called int main (void) Words mywords = { ARRAY-SIZE, { "stuff", " and", " nonsense" } }; char* ful!String = NULL; int returnValue EXIT SUCCESS; fullstring = alloccat(&myWords ); //calls the function you write below if (ful ! String== NULL) // get out if memory not allocated fprintf (stderr, "Could not allocate memory\n" returnValue = EXIT FAILURE ; else puts (fullstring); free (fullString); // prints out the new string // releases memory getch ); return returnValue this sample code above would print out stuff and nonsense ! WARNING: The code given above is an example of how the function might be used. Do not try to use the sample code above in the function definition! The function has no ilo! Hint: This function will need to calculate the length of the strings passed in. It needs to be able to work with ANY STRINGS, not just those shown in the example char* allocCat(

Answer 1

The solution for the given program is given below with the screenshot of output.

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I have not used iostream and fstream as you asked in question. I kept the code simple and made

it similar to c, so it could be easily understood.

I have added comments to program, if there is anything else do let know in comments.

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=================== CODE TO COPY ===========================

#include <cstdio>
#include <cstdlib>

// structure for words struct
struct words{
int word_count;
char theWords[1024][80];
};

// typedef for struct words
typedef struct words Words;

// function prototype
char * allocCat( const Words * w);

int main() {

// here we are adding 4 words to onu struct
Words words_array = { 4, { "writting" , "a", "c++", "program" } };

// passing the address of struct to function
char *new_sentence = allocCat( &words_array );

// if memory Could not be allocated we print msg and return
if ( new_sentence == NULL )
{
fprintf(stderr, "Could not allocate memory for words\n");
return 1;
}

fprintf(stdout, "New string is %s\n", new_sentence );
free( new_sentence );
return 0;

}

char * allocCat( const Words * w){
  
// calculating how many elements are there in the array
int array_length = w->word_count;
  
//printf("The number of elements in array %d ", array_length);
  
int element_length = sizeof(w->theWords[0]);
//printf("The length of elements in array %d ", element_length);
  
char *p = ( char *)malloc( array_length * element_length );
char *temp = p;
  
// if we cannot allocate space return null
if ( p == NULL )
return NULL;
  
// add all elements togather and return this pointer
for (int i = 0 ; i < array_length; i++ )
{
int j = 0;
while ( *temp++ = w->theWords[i][j++] );
temp--;
}
  
  
return p;
}

=========================================================

output :

gcc version 4.6.3 New string is writtingac++program 2