Adding Arrays

I have done this very simple program a few times and it worked. Now its not and I cannot figure it out.

Code:

---

#include <stdio.h>

#define MAXNUMBER 11


void addfloat(float *, float *);


int main(int argc, const char * argv[])
{


float array1[MAXNUMBER] = {10.2,12.8,11.9,18.3,19.5,29.8,19.4,15.4,13.6,13.8};
float array2[MAXNUMBER] = {11.2,17.5,12.6,13.1,11.3,19.3,9.4,5.4,3.6,3.8};

  addfloat(&array1[MAXNUMBER], &array2[MAXNUMBER]);

  return 0;
}


void addfloat(float array1[],float array2[])
{
  int i;
  float sum[MAXNUMBER];

  for (i=1; i < MAXNUMBER; i++) {

      sum[i] = array1[i] + array2[i];

printf("Array1 + Array2 = %4.2f\n",sum[i]);
}
}

---

Code:

---

#include <stdio.h>


#define MAXNUMBER 11




void addfloat(float * array1, float * array2);




int main( )
{
    float array1[MAXNUMBER] = {10.2,12.8,11.9,18.3,19.5,29.8,19.4,15.4,13.6,13.8};
    float array2[MAXNUMBER] = {11.2,17.5,12.6,13.1,11.3,19.3,9.4,5.4,3.6,3.8};


    addfloat(array1, array2);


  return 0;
}




void addfloat(float * array1,float * array2)
{
    int i;
    float sum[MAXNUMBER];


    for (i=1; i < MAXNUMBER; i++)
    {
        sum[i] = array1[i] + array2[i];
        printf("Array1 + Array2 = %4.2f\n",sum[i]);
    }
}

---

I'll get to what I did here in a few minutes.

Quote:

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Originally Posted by jocdrew21

I have done this very simple program a few times and it worked. Now its not and I cannot figure it out.

Code:

---

#include <stdio.h>

#define MAXNUMBER 11


void addfloat(float *, float *);


int main(int argc, const char * argv[])
{


float array1[MAXNUMBER] = {10.2,12.8,11.9,18.3,19.5,29.8,19.4,15.4,13.6,13.8};
float array2[MAXNUMBER] = {11.2,17.5,12.6,13.1,11.3,19.3,9.4,5.4,3.6,3.8};

  addfloat(&array1[MAXNUMBER], &array2[MAXNUMBER]);

  return 0;
}


void addfloat(float array1[],float array2[])
{
  int i;
  float sum[MAXNUMBER];

  for (i=1; i < MAXNUMBER; i++) {

      sum[i] = array1[i] + array2[i];

printf("Array1 + Array2 = %4.2f\n",sum[i]);
}
}

---

---

Step 1 : Fixed all of the indentation that was off in your code.

Step 2 : Changed the function prototype to include the proper variable names instead of just a type like you probably did by mistake.

Step 3 : You over-complicated the calling of the addfloat function. You just needed to pass a float pointer to it and you didn't need to include the types or anything.

Step 4 : Fixed the addfloat function to just use float pointers instead of pointers to float pointers.

Step 5 : Ran the program.

Quote:

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Step 2 : Changed the function prototype to include the proper variable names instead of just a type like you probably did by mistake

---

There is nothing technically wrong with his function prototype. However many people consider it a good practice to add the names, but it's not a requirement. The compiler doesn't actually use the variable names in the prototype, it's the names in the implementation that are important.

Quote:

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Step 4 : Fixed the addfloat function to just use float pointers instead of pointers to float pointers.

---

Do you realize that the following are equivalent?

Code:

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void addfloat(float *, float *);
void addfloat(float[], float[]);

---

Also unless you're going to actually use the parameters to main() you shouldn't use that version. And the argv[][] argument should not be declared const.

Jim

Quote:

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Originally Posted by jimblumberg

There is nothing technically wrong with his function prototype. However many people consider it a good practice to add the names, but it's not a requirement. The compiler doesn't actually use the variable names in the prototype, it's the names in the implementation that are important.


Do you realize that the following are equivalent?

Code:

---

void addfloat(float *, float *);
void addfloat(float[], float[]);

---

Also unless you're going to actually use the parameters to main() you shouldn't use that version. And the argv[][] argument should not be declared const.

Jim

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1) I didn't know that, I've always been taught to add names in prototypes.
2) I do, but I'm used to using pointers instead of arrays.

Quote:

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Originally Posted by HelpfulPerson

1) I didn't know that, I've always been taught to add names in prototypes.

---

You do it (as a lot of other things like indentation) for programmer reading the code, not for compiler.

Quote:

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2) I do, but I'm used to using pointers instead of arrays.

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Do you know a pointer is designated with a *, the [] denote arrays.

Jim

Quote:

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Originally Posted by jimblumberg

Do you know a pointer is designated with a *, the [] denote arrays.

Jim

---

I know that? Why are you asking me that?

Quote:

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Why are you asking me that?

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Because you don't seem to understand the concept.

Code:

---

// His original.
void addfloat(float * array1,float * array2)
{
// Your modification.
void addfloat(float array1[],float array2[])

---

And then your statement:

Quote:

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2) I do, but I'm used to using pointers instead of arrays.

---

His original code is using pointer notation, your's is using array notation.

Jim

Thank you very much!!!

Quote:

---

Originally Posted by HelpfulPerson

Code:

---

#include <stdio.h>


#define MAXNUMBER 11




void addfloat(float * array1, float * array2);




int main( )
{
    float array1[MAXNUMBER] = {10.2,12.8,11.9,18.3,19.5,29.8,19.4,15.4,13.6,13.8};
    float array2[MAXNUMBER] = {11.2,17.5,12.6,13.1,11.3,19.3,9.4,5.4,3.6,3.8};


    addfloat(array1, array2);


  return 0;
}




void addfloat(float * array1,float * array2)
{
    int i;
    float sum[MAXNUMBER];


    for (i=1; i < MAXNUMBER; i++)
    {
        sum[i] = array1[i] + array2[i];
        printf("Array1 + Array2 = %4.2f\n",sum[i]);
    }
}

---

I'll get to what I did here in a few minutes.

---

Quote:

---

Originally Posted by jimblumberg

Because you don't seem to understand the concept.

Code:

---

// His original.
void addfloat(float * array1,float * array2)
{
// Your modification.
void addfloat(float array1[],float array2[])

---

And then your statement:

His original code is using pointer notation, your's is using array notation.

Jim

---

Ummm, no. If you looked at where I posted the code that I fixed, then you would see that I didn't modify any of his functions in the way you are suggesting. I did leave the way he accessed the pointer as an array inside the function the same.

Code:

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I must be having a bad day but I am getting the wrong values for total. total+=sum should store the last value, correct. sum0=21,sum1=30.3 etc. I am storing it and adding it them together in total. However I keep getting701.80 and I need 271.9. What is the deal here. It is add up every number on each line over and over?

---

Code:

---

#include <stdio.h>
#define MAXNUMBER 10

void addfloat(float * array1, float * array2);

int main( )
{
    float array1[MAXNUMBER] = {10.2,12.8,11.9,18.3,19.5,29.8,19.4,15.4,13.6,13.8};
    float array2[MAXNUMBER] = {11.2,17.5,12.6,13.1,11.3,19.3,9.4,5.4,3.6,3.8};
   
    addfloat(array1, array2);
   
    return 0;
}

void addfloat(float * array1,float * array2)
{
    int i;
    float sum[MAXNUMBER];
    float total[MAXNUMBER];
   
    for (i=0; i < MAXNUMBER; i++)
    {
        sum[i] = array1[i] + array2[i];
        total[i]+= sum[i];
        printf("%4.1f + %4.1f = %4.1f\n",array1[i],array2[i],sum[i]);

    }
    printf("-----------------------\n");
    printf("TOTAL:%14.3f",total[i]);
}

---

I even tried

Code:

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total[i]= sum[0]+sum[i+1];

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total shouldn't be an array. Are there many totals or only one? I assume only one. And it of course needs to be initialized to 0.

I could have swore I did that but it didn't work. However I just did it and it worked.

I am just going to keep making up programs and keep practicing. C++ starts in two weeks, any advice?

Data Structures and Data Files are still giving me issues, I really need to practice those things a lot more.