Question

I’m brand new to programming..im just trying to make my own program to find the volume and surface area of spheres and cylinders. I cant figure out why this program keeps crashing before it will get to the rest of the code. I’m guessing the char* might be wrong but i cant see why it would be.

int main()
{
    char* solid;
    char* unit;
    printf("Welcome to the Center of Spheres and Cylinders!\n");
    printf("Would you like to look at a Sphere or a Cylinder?: ");
    scanf("%s", solid);
        if(solid == "Cylinder" || solid == "cylinder")
        {
            printf("You chose to look at a Cylinder.\n");

        else if(solid == "Sphere" || solid == "sphere")
        {
            printf("You chose to look at a Sphere.\n");

it crashes just after I input for scanf...when i type in either cylinder or sphere it crashes. Thank you for the help

Answer 1

solid is a character pointer, it is not pointing to any allocated memory location which is causing your program crash when you try to read data into it with scanf() ( and which is why it crashes right after that call as you observe).

After you declare

 char *solid;

you should malloc() a certain amount of storage for it to point to. Alternatively you could have declared an array named solid

 char solid[100];

Note that the crash is actually a good thing in that it is helpful to show there’s a problem with an errand pointer. This may not always happen unfortunately depending on where a pointer in memory is pointing too.