Parsing Help

[popnfresh12321]

I ran this on two compilers. One gave me a seg fault, the other runs it fine.

void parse(char *line)
{
    char temp;
    int i;
    int j;
    int k, l;
    int length = 0;
    char *string = malloc(sizeof(char) * 50);
    char *firstName  = malloc(sizeof(char) * 50);
    char *lastName  = malloc(sizeof(char) * 50);
    
    do{
        if((*(line + i)>=65)&&(*(line + i)<=90))
        {
            k = 0;
            l= 0;
            j = i;
            while(*(line + j) != ' '){
                j++;
            }
            j++;
            while(*(line + j) != ' '){
                j++;
            }
            for(k = i; k < j; k++)
            {
                *(string + l) = *(line + k);
                l++;
            }
            //when I'm done it will pass string to another function that will check if it is a name or not, but for now I'm just printing it.
            printf("%s\n", string);

        }
        i++;
    }while(i < 100);

}

Any ideas as to why I get a segfault with one compiler? Or ways I can improve this?

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Initialise the variable 'i'