getting a "invalid operands to binary"

I am getting this error in lines that involve "ch[_]" in lines 27, 28, 29, 33, 42, 43, 44, and 48, heres the code:

Code:

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


struct integer{
    int* digits;
    int size;
};
FILE *IFP;
//convert string to int array




struct integer* multiply(struct integer *p,  struct integer *q){
    struct integer *done = malloc(sizeof(struct integer));
    struct integer *temp = malloc(sizeof(int) * 1000000000);
    struct integer *ch = malloc(sizeof(char) * 1000000000);
    done->digits = malloc(sizeof(int) * (done->size + 1));
    int i = 0, j = 0, k = 0, d = 0, l1, l2;
    long int carry = 0;


    l1 = p->size - 1;
    l2 = q->size - 1;
    if (l1 >= l2){
        for (i = l2; i >= 0; i--){
            for (j = l1; j >= 0; j--){
                ch[k] += (q->digits[i] * p->digits[j] + carry) % 10;
                temp[k] = ch[k] % 10;
                temp[k+1] = ch[k] / 10;
                k++;
                carry = (q->digits[i] * p->digits[j] + carry) / 10;
            }
            temp[k++] += carry;
            carry = 0;
            ch = temp;
            d++;
            k = d;
        }
    }else{
        for (i = l1; i >= 0; i--){
            for (j = l2; j >= 0; j--){
                ch[k] += (q->digits[j] * p->digits[i] + carry) % 10;
                temp[k] = ch[k] % 10;
                temp[k+1] = ch[k] / 10;
                k++;
                carry = (q->digits[j] * p->digits[i] + carry) / 10;
            }
            temp[k++] += carry;
            carry = 0;
            ch = temp;
            d++;
            k = d;
        }
    }
    done->digits = temp;
    return done;
}


struct integer* convert_integer(char* stringInt){
    struct integer *converted = malloc(sizeof(struct integer));
    int length, i, *ints;
    ints = (int *)malloc(10001 * sizeof(int));
    length = strlen(stringInt);
    converted->size = length;
    for(i = length; i > 0; i--)
        ints[i - 1] = (stringInt[length - i]-48);
    converted->digits = ints;
    return converted;
}


void print(struct integer *a){
    int len = a->size;
    int i, j;
    for(i = 1000000000; i >= 0; i--){
        if (a->digits[i] != 0){
            for (j = i; j >= 0; j--){
                printf("%d", a[j]);
            }
            break;
        }
        printf("\n");
    }
}


int main(){
    IFP = fopen("bigint.txt", "r");
    char *num1, *num2;
    num1 = (char *)malloc(10001 * sizeof(char));
    num2 = (char *)malloc(10001 * sizeof(char));
    struct integer *snum1 = malloc(sizeof(struct integer));
    struct integer *snum2 = malloc(sizeof(struct integer));
    struct integer *total = malloc(sizeof(struct integer));
    int i, j, runs = 0;
    fscanf(IFP, "%d", &runs);
    printf("runs: %d\n", runs);
    for (i = 0; i < runs; i++){
        fscanf(IFP, "%s %s", num1, num2);
        printf("Problem #%d: ", runs+1);
        snum1 = convert_integer(num1);
        print(snum1);
        printf(" * ");
        snum2 = convert_integer(num2);
        print(snum2);
        printf(" = ");
        total = multiply(snum1, snum2);
        //print(total);
    }
    free(snum1->digits);
    free(snum1);
    free(snum2->digits);
    free(snum2);
    fclose (IFP);
    return 0;
}

the lines appear to be off, sorry for this

Code:

t.c:31:23: error: invalid operands to binary + (have ‘struct integer’ and ‘long int’)
t.c:32:33: error: invalid operands to binary % (have ‘struct integer’ and ‘int’)
t.c:33:35: error: invalid operands to binary / (have ‘struct integer’ and ‘int’)
t.c:37:23: error: invalid operands to binary + (have ‘struct integer’ and ‘long int’)
t.c:46:23: error: invalid operands to binary + (have ‘struct integer’ and ‘long int’)
t.c:47:33: error: invalid operands to binary % (have ‘struct integer’ and ‘int’)
t.c:48:35: error: invalid operands to binary / (have ‘struct integer’ and ‘int’)

What the compiler is telling you is "I don't know how to <operator> a struct integer and an integer". Where <operator> is + & or / etc.. shown above. Meaning you can't perform mathematical operations on a "struct integer", only on integer/floating point types. So you have to reference a member INSIDE the "struct integer" instead and use THAT in the operator (as an operand). If you read the errors its actually quite clear the problem.

EDIT:
If it's not obvious "binary" in this case means "takes 2 arguments" ie, + takes 2 "operands" a + b, a and b are operands.

okay i fixed it and now it is just crashing, any reason known?

Code:

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


struct integer{
    int* digits;
    int size;
};
FILE *IFP;
struct integer* multiply(struct integer *p,  struct integer *q){
    struct integer *done = malloc(sizeof(struct integer));
    int *temp = malloc(sizeof(int) * 1000000000);
    int *ch = malloc(sizeof(char) * 1000000000);
    done->digits = malloc(sizeof(int) * (done->size + 1));
    int i = 0, j = 0, k = 0, d = 0, l1, l2;
    long int carry = 0;
    l1 = p->size - 1;
    l2 = q->size - 1;
    if (l1 >= l2){
        for (i = l2; i >= 0; i--){
            for (j = l1; j >= 0; j--){
                ch[k] += (q->digits[i] * p->digits[j] + carry) % 10;
                temp[k] = ch[k] % 10;
                temp[k+1] = ch[k] / 10;
                k++;
                carry = (q->digits[i] * p->digits[j] + carry) / 10;
            }
            temp[k++] += carry;
            carry = 0;
            ch = temp;
            d++;
            k = d;
        }
    }else{
        for (i = l1; i >= 0; i--){
            for (j = l2; j >= 0; j--){
                ch[k] += (q->digits[j] * p->digits[i] + carry) % 10;
                temp[k] = ch[k] % 10;
                temp[k+1] = ch[k] / 10;
                k++;
                carry = (q->digits[j] * p->digits[i] + carry) / 10;
            }
            temp[k++] += carry;
            carry = 0;
            ch = temp;
            d++;
            k = d;
        }
    }
    for(i = 1000000000; i >= 0; i--){
        if (temp[i] != 0){
            for (j = i; j >= 0; j--){
                printf("%d", temp[j]);
            }
            break;
        }
        printf("\n");
    }
    done->digits = temp;
    return done;
}


struct integer* convert_integer(char* stringInt){
    struct integer *converted = malloc(sizeof(struct integer));
    int length, i, *ints;
    ints = (int *)malloc(10001 * sizeof(int));
    length = strlen(stringInt);
    converted->size = length;
    for(i = length; i > 0; i--)
        ints[i - 1] = (stringInt[length - i]-48);
    converted->digits = ints;
    return converted;
}


int main(){
    IFP = fopen("bigint.txt", "r");
    char *num1, *num2;
    num1 = (char *)malloc(10001 * sizeof(char));
    num2 = (char *)malloc(10001 * sizeof(char));
    struct integer *snum1 = malloc(sizeof(struct integer));
    struct integer *snum2 = malloc(sizeof(struct integer));
    struct integer *total = malloc(sizeof(struct integer));
    int i, j, runs = 0;
    fscanf(IFP, "%d", &runs);
    for (i = 0; i < runs; i++){
        fscanf(IFP, "%s %s", num1, num2);
        printf("Problem #%d: ", i + 1);
        snum1 = convert_integer(num1);
        for(j = 0; j < snum1->size; j++)
            printf("%d",snum1->digits[snum1->size - j - 1]);
        printf(" * ");
        snum2 = convert_integer(num2);
        for(j = 0; j < snum2->size; j++)
            printf("%d",snum2->digits[snum2->size - j - 1]);
        printf(" = ");
        total = multiply(snum1, snum2);
    }
    free(snum1->digits);
    free(snum1);
    free(snum2->digits);
    free(snum2);
    fclose (IFP);
    return 0;
}

Code:

void print(struct integer *a){
    int len = a->size;
    int i, j;
    for(i = 1000000000; i >= 0; i--){ /* Mistake in this Line */
        if (a->digits[i] != 0){       /* Off by one  mistake in this line */
            for (j = i; j >= 0; j--){ /* or in this line */
                printf("%d", a[j]);   /* Mistake in this Line */
            }
            break;
        }
        printf("\n");
    }
}

Tim S.

You are allocating enough space that it might be crashing because it fails.

int *temp = malloc(sizeof(int) * 1000000000); /* I estimate this as 4000 MB the normal safe amount is around 10 MB */

Code:

    int *temp = malloc(sizeof(int) * 1000000000);
    if (temp == NULL){
        fprintf(stderr, "malloc of temp failed\n");
        exit(1);
    }

When I added the above it it printed the failed message.


Tim S.

Your program attempts to allocate 5GB, plus an uninitialised amount (done->size) which could easily also be up to another 4GB.
A 32-bit process in Windows, for example, can only allocate 2GB in total, and usually not all at once.
You need to be a lot starter about your allocation requests.

FYI: I posted test code for someone else doing what appears to be the same assignment in this thread.
Can someone try to explain what my professor is talking about...