Debug Assertion Failed!

[sherlock111]

I am new to C++ and this forum. When I was working on my assignment, a 'string subscript out of range' error keeps occuring in Line 1441.

The partial code is as follow:

string naming(string lines[],string name[]) {
	for (int i = 0 ; i<= 99 ; i++) {
		int  j = 0;
    while (!(lines[i][j] >= '0' && lines[i][j] <= '9')) {
		j++; } 
   name [i] = lines[i].substr(0,j-2);
	}
	return name[100];
}

The above function inputs an array(lines) input from a text file storing at most 100 students' names and other integers(separated by a space), what I want is to place all the names in another arrays (name). While in debugging, the mentioned error keeps occuring. How could I solve it? If you would require further information, please let me know.

Thank you so much.

[Chervil]

Each string has a particular length, for example
lines[i].size()

Your code doesn't check that the index j is within this limit.

Also, you say the array will have at most 100 lines, but the loop attempts to process the full 100 lines (even if that line is empty).

[sherlock111]

Thank you for your answer. I tried to solve the problem by declaring a global variable to count the number of lines in the getline function when I input the file into array, lines. Also, I adjusted the code such that it become:

string naming(string lines[],string name[]) {
	for (int i = 0 ; i<= number_of_lines ; i++) {
		int  j = 0;
    while (!(lines[i][j] >= '0' && lines[i][j] <= '9')) {
		j++;
    if (j <= lines[i].length())
	continue;
	else break;} 
   name [i] = lines[i].substr(0,j-2);
	}
	return name[100];
}

However, this time, when I debug, it says ' an unhandled win32 exception occured in (my programme cpp file)[3800].

[Chervil]

Maybe like this, test the string length before accessing its contents.
And notice < rather than <=

string naming(string lines[],string name[]) 
{
    for (int i = 0 ; i < number_of_lines ; i++) 
    {
        int  j = 0;
        
        while ((j < lines[i].length()) && (!(lines[i][j] >= '0' && lines[i][j] <= '9'))) 
        {
            j++;
        }
        
        name [i] = lines[i].substr(0,j-2);
    }
    return name[100]; // not sure about this line ????
}