I'm trying to store a string in a char variable using sprintf. The code compiles, but when I run it I get a stack buffer overflow error. My compiler gives me information about why there was an error, but I can't tell what is actually wrong.
int numbers[] is an array with length 6, and matchHighest is an integer = 0.
I called match6 in this function:
int match(int numbers[], int matchHighest){
int matchArray[] = {0, 0, 0, 0, 0};
int i = 0;
char m6[100] = "";
char *m6p = m6;
match6(&numbers[i], matchArray, &m6[100]);
Here is where the error is occuring:
int match6 (int numbers[], int matchArray[5], char *m6){
int i=0;
while((numbers[i]==numbers[i+1]) && (i<5)){
i++;
}
if(i == 5){
matchArray[4] = 6 * numbers[0] + 27;
sprintf(m6, "Rule match-6(%d) - score %d", numbers[0], matchArray[4]);
printf("%s\n", m6);
}
return matchArray[4];
}
When it runs, I get this error (all the values at the bottom are correct and as expected):
draft6.c:98 runtime error - stack buffer overflow
dcc explanation: access past the end of a local variable. Make sure the size of your array is correct. Make sure your array indices are correct.
Execution stopped here in match6(4) - score 51") in draft6.c at line 98:
if(i == 5){
matchArray[4] = 6 * numbers[0] + 27;
--> sprintf(m6, "Rule match-6(%d) - score %d", numbers[0], matchArray[4]);
printf("%s\n", m6);
}
Values when execution stopped:
i = 5
m6 = "Rule match-6(4) - score 51"
matchArray[4] = 51
numbers[0] = 4
match6(&numbers[i], matchArray, &m6[100]);
. You pass the address of the item beyond the last allocated item. After which match6 writes out of bounds. Instead of doing strange things, simply pass the array:
char m6[100] = "";
match6(&numbers[i], matchArray, m6);
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