Program segfaults when I call the atoi() function

Question

I am having segfaulting problems with my program that is supposed to read in a file containing bowling scores and then output your total score, it calls the atoi() function it segfaults.

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

/*
int myAtoi(char *str)
{
    int res = 0, i; // Initialize result

    // Iterate through all characters of input string and update result
    for (i = 0; str[i] != '\0'; ++i)
        res = res*10 + str[i] - '0';

    // return result.
    return res;
}
*/

//Cleans and totals the values
int cleanValues(char *values)
{
    //debug
    puts(values);
    //declares vars
    int i, total=0, temp;
    //iterates through the array converting and totaling the integer values.
    for(i=0; i!=37; ++i)
    {
        //converts and stores the values in temp
        temp = atoi(values[i]);
        //atoi() returns a zero when it the value is not a number and if the value it is zero it wouldn't mater anyways so in both cases we skip it here.
        if(temp != 0)
            //adds temp to the total.
            total+=temp;
        else
                //increments i
                    ++i;
        //debug
        printf("%c %d %d\n",values[i], i, total);
    }
    //returns the total value which is then returned to the main by readFile()
    return total;
}

//reads the file, the name of the file is passed from the main().
int readFile(char *name)
{
    //creates the array to hold the read values
    char values[37];
    //creates a pointer to a memory location where we store the file
    FILE *filePointer;

    //opens the file for reading
    filePointer=fopen(name, "r");

    //checks to see if the file contains a information.
    if(filePointer == NULL)
    {
        printf("File %s is not available\n", name);
        exit(1);
    }

    //reads from the file and shoves it into the array
    fgets(values, 37, filePointer);

    //debugging output for checking the value of values
    puts(values);

    return cleenValues(values);

}


//the main function... this shouldn't require an explanation... it is the running part of the program! OK there I said it!
int main(int argc, char* argv[])
{
    //checks to see if the program has been called correctly using the command line arguments
    if(argc!=2)
    {
         printf("USEAGE: %s nameOfTheInputFile\n", argv[0]);
         return 0;
    }
    //prints the total score by returning the value of mathing()
    printf("Your total score is: %d",readFile(argv[1]));

    return 0;
}

Does anyone know why it is segfaulting? I am very confused and so is everyone who I have shown to, any and all help is appreciated.

Here is the GDB stepping right before it breaks.

38                      temp = atoi(values[i]);
   atoi (str=0x39 <Address 0x39 out of bounds>) at Bowling.c:19
19          int res = 0, i; // Initialize result
22          for (i = 0; str[i] != '\0'; ++i)
   Program received signal SIGSEGV, Segmentation fault.
   0x0000000100401126 in atoi (str=0x39 <Address 0x39 out of bounds>) at Bowling.c:22
22          for (i = 0; str[i] != '\0'; ++i)
      1 [main] a 5640 cygwin_exception::open_stackdumpfile: Dumping stack trace to a.exe.stackdump
[Inferior 1 (process 5640) exited with code 0105400]

If i am reading this right, it is saying that the array is exceeding its assigned memory or something.

Can you please minimize the code such that it will still compile and run but will contain only the bits and pieces needed to reproduce your bug? — Mihai Maruseac, Apr 25 '14 at 02:38
By enabling all compiler warnings, you would have save yourself time as it would have directed you to the problem right away. — chux - Reinstate Monica, Apr 25 '14 at 02:49
A compiler which doesn't warn for this would be non-conforming, so I suspect it is more of a case of OP ignoring the warnings. — M.M, Apr 25 '14 at 04:14
@MihaiMaruseac, will do that in the future, sorry. MattMcNabb Yep that sums it up, i'm a dumbass. Sorry for the bad question, first time here and didn't know how to phrase it :P — Mike Shlanta, Apr 25 '14 at 14:14

score 3 · Accepted Answer · answered Apr 25 '14 at 02:42

You are passing a character into atoi, when you should be passing in a string. I suppose you could change

atoi(values[i])

to

atoi(values)

although you would no longer need the for loop. I'm not entirely certain what purpose the loop is meant to serve anyway. You should be able to convert the string to an integer with a single call.

score 3 · Answer 2 · answered Apr 25 '14 at 04:10

you are passing value[i] which is a character and in atoi function you are dereferencing that character value which leads to an access of memory location which is restricted leading to segmentation fault.

According to your atoi function you have to pass a string as argument of atoi function.

Program segfaults when I call the atoi() function

2 Answers2