Styjun

I have a char array "2468" that I want to convert to an int array for easy mathematic manipulations. But when I run the project it just says the 'Core dumped' error. I don't know what could cause that...

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

int main() 
 int i = 0;
 char charArray[] = "2468";
 int intArray[20];
 for (i = 0; i < strlen(charArray); ++i) 
 intArray[i] = atoi(charArray[i]);
 printf("%d", intArray[i]);
 
 return 0;

You should read the warnings. They are there to help you:

b.c: In function ‘main’:
b.c:11:37: warning: passing argument 1 of ‘atoi’ makes pointer from integer without a cast [-Wint-conversion]
 intArray[i] = atoi(charArray[i]);
 ~~~~~~~~~^~~
In file included from b.c:4:
/usr/include/stdlib.h:104:30: note: expected ‘const char *’ but argument is of type ‘char’
 extern int atoi (const char *__nptr)
 ~~~~~~~~~~~~^~~~~~

But apart from that, why complicate things? Since you want to copy digits rather than numbers, just do like this:

for (i = 0; i < strlen(charArray); ++i) 
 intArray[i] = charArray[i] - '0';

If you want to guard against errors, check with isdigit(charArray[i]) first. Remember that atoi will return 0 on error, so if you get a 0, you will know know if the conversion worked or not.

You need to convert each char in charArray into a string to pass to atoi:

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

int main() 
 int i = 0;
 char charArray[] = "2468";
 int intArray[20];
 for (i = 0; i < strlen(charArray); ++i) 
 // Convert character to string
 char convert[2] = charArray[i], 0;
 // Pass string to atoi
 intArray[i] = atoi(convert);
 printf("%d", intArray[i]);
 
 return 0;

int main() 
 int i = 0;
 char charArray[] = "2468";
 int intArray[20];
 while(charArray[i])
 
 intArray[i] = charArray[i] - '0');
 printf("%d", intArray[i++]);
 
 return 0;

Two functions: first converts chars from the string to their digit values, the second converts table pointers to strings to numbers.

void convert_charsToDigits(const char *str, int *arr)

 int c;
 while(*str)
 
 if(!isdigit(c = *str++)) continue;
 *arr++ = c - '0';
 


void convert_stringsToInts(const char **str, int *arr) //Takes NULL terminated string table

 while(*str)
 
 *arr++ = atoi(*str++);
 

usage

char *cstr = "696"
char *str = "2345", "455667", NULL;
int arr[5];

convert_charsToDigits(cstr, arr);
convert_stringsToInts(str, arr);