Array of of Struct containing array of char as members - C [closed] - c

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I have a struct like this:
struct vertices{
char x[20];
char y[20];
char z[20];
};
and then in main I have an array of the struct vertices like this:
struct vertices vert[64];
plus an array of char in my main function like this:
char exampleArray[200]="v 23.232000 32.33000 2.03900\nv 9.20900 3.29000 1.0002\n";
so what I want to do is to parse this big array containing a hundred or so vertices, and store each value in the corresponding x,y,z char arrays of the struct vertices, which later I'm gonna simply convert by calling on
float x=atof(vert[1].x) and draw each one.
But the problem is that I can't store , copy, concat characters from the raw array to the x,y,z arrays by any ways, i tried to do it by vert[0].x=exampleArray[0], vert[0].x=exampleArray+i etc inside different conditions like
if(SpaceCount==1)
{
vert[0].x[0]=exampleArray[i];
i++;
}
but all this doesn't work.
I tried so many variations, couldn't list them all.
But the thing I want is to parse the exampleArray which has my vertices in raw format, every 3D vertix has spaces in between them, every vertix starts with a char V followed by a space, the first point is the X then followed by a space and then the Y point and after the Z point there is newline \n character and then again a V for a new vertix.

Answer 1

You could use strtok() with delimiter " \n" to get each piece and then strcpy() to place each token in your struct.
struct vertices {
char x[20];
char y[20];
char z[20];
};
int main(void)
{
char exampleArray[200] = "v 23.232000 32.33000 2.03900\nv 9.20900 3.29000 1.0002";
char *toStrtokVertex, *token;
char delim[5] = " \n";
struct vertices V[10];
int i = 0;
toStrtokVertex = exampleArray;
while ((token = strtok(toStrtokVertex, delim)) != NULL) {
// ignore the `v`
// get x
if ((token = strtok(NULL, delim)) != NULL) {
strcpy(V[i].x, token);
}
else {
printf("INPUT ERROR\n");
exit(1);
}
// get y
if ((token = strtok(NULL, delim)) != NULL) {
strcpy(V[i].y, token);
}
else {
printf("INPUT ERROR\n");
exit(1);
}
// get z
if ((token = strtok(NULL, delim)) != NULL) {
strcpy(V[i].z, token);
}
else {
printf("INPUT ERROR\n");
exit(1);
}
// switch this to NULL to keep parsing the same string
toStrtokVertex = NULL;
i++;
}
for (int j = 0; j < i; j++) {
printf("V[%d] (%s, %s, %s)\n", j, V[j].x, V[j].y, V[j].z);
}
}
Note that I modified your input value to match your description. You had
"v 23.232000 32.33000 2.03900\n 9.20900 3.29000 1.0002"
which did not have a v after the \n to start the next vertex, so I added a v
"v 23.232000 32.33000 2.03900\nv 9.20900 3.29000 1.0002"

Answer 2

Character arrays are not copied by simply pointing at them. The function "strcpy(vert[0].x, &exampleArray[2])" is needed, but even then there is no '\0' immediately after that first number to indicate where to stop reading. "memcpy" does not need a NULL ('\0') but needs a length based on spaces.
Further, the "atof" operation to plan to use requires a NULL terminator as well.
I am concerned with your "space planning". You have 64 copies of structures that will each require 60 characters (3840 total), but your exampleArray only has 200. And the input string exampleArray has strings for numbers that must be no longer than 19 digits/decimals because you need the NULL terminator in each of x/y/z to exist.
This is the pure technical evaluation of code issues, but your original post does not show more of the application design. Help us understand your application design and more advice can be given.