Finding characters within a string in C

I'm wri开发者_运维技巧ting an algorithm in C with netbeans to find asterisks in a string.

int main() {
    int M=0, i, j;
    scanf("%i",&M);
    int pos[M];
    char c[M];
    scanf("%s", c);

    i=0;
    j=1;

    while(c[i] != '\0'){
        if(c[i]=='*'){
            pos[j] = i;
            j++;
        }
        i++;
    }

    printf("Asterisks in positions: \n\n");

    for(j=1; j<=i; j++){
        printf("%i", pos[j]);
    }
    return 0;
}

But it doesn't work, it prints a lot of numbers even if M is a small number.

---

The problem seems to be you never take into account the number of characters found. You print the whole vector, using i instead of j to iterate. It's j that holds the number of matches.

Also, try using strchr, from cstring :)

Get the first position, then search again from the next character until null is returned.

---

The information regarding how many asterisks you found is stored in the counter j. This variable gets reset in the for loop:

for(j=1; j<=i; j++)

Furthermore, this for loop goes all the way up to i, which is the length of the your input string. Try reworking your loop as follows:

for(i=1; i<j; i++){    
    printf("%i", pos[i]);    
} 

---

After your while loop completes, j holds the total number of positions recorded, so you should be printing from pos[1] to pos[j]. Your current loop prints from pos[1] to pos[i]. Just invert the variables in your final loop:

for(i=1; i<=j; i++){
    printf("%i", pos[i]);
}