put a string with numbers and letters into an int pointer within a struct

Question

typedef struct Int40
{
  int *digits;
} Int40;




  Int40 *parseString(char *str)
{
    Int40 *p;

    int i;
    int *intPtr;
    printf(\"%s\\n\", str);

    p->di         


        

Answer 1

It looks like you are confused about a few things.

1) Memory allocation

 p->digits = malloc(sizeof(str) + 1);

This is allocation for string but p->digits is a pointer of int type.

2) The function atoi

int atoi(const char *str);

Returns int value. Maximum value for a variable of type int is 2147483647 Check: limits.h.

If you use long long int it can give you 19 digits. Do you need more digits than long long int can give you?

3) Remember to allocate memory for the structure and also remember to release it.

Check the following program:

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

typedef struct LLint19
{
   long long int *digits;
} LLInt19;

long long int sg7_atoi(const char *c)
{
    long long int value = 0;
    int sign = 1;
    if( *c == '+' || *c == '-' )
    {
        if( *c == '-' ) sign = -1;
        c++;
    }
    while (*c >= '0' && *c <= '9') // to detect digit == isdigit(*c))
    {
        value *= 10;
        value += (int) (*c-'0');
        c++;
    }
    return (value * sign);
}

LLInt19 *parseString(char *str)
{
    LLInt19 *p;
    long long int *value;

    printf("Input  str: %s\n", str);

    value = malloc (sizeof(long long int) ); // allocate memory for long long int value

    p = malloc( sizeof(LLInt19) );           // allocate memory for the structure

    *value  = sg7_atoi(str);                 // do a conversion string to long long int

    p->digits = value;

    return p;
}

int main(int argc, char *argv[])
{
    LLInt19 *p;

    char test1[] = "1234567890123456789";

    p = parseString(test1);

    printf("Output str: %lld \n", *p->digits);

    free(p->digits);
    free(p);

    return 0;
}

Output:

Input  str: 1234567890123456789                                                                                                             
Output str: 1234567890123456789