FreeBasic Bare Bones: Difference between revisions
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Pointers can be difficult to understand. Many modern languages do not work with pointers, while if you know a language like C, C++ or Assembly, you will probably know what they do. Since you will need to use them, a quick introduction in how they work in FreeBasic. |
Pointers can be difficult to understand. Many modern languages do not work with pointers, while if you know a language like C, C++ or Assembly, you will probably know what they do. Since you will need to use them, a quick introduction in how they work in FreeBasic. |
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The computer uses a set of registers, and memory. Memory is divided into bytes, each byte has its own location number. Big numbers, strings, types and arrays use up multiple bytes. These bytes are stored next to each other. A Long will hold |
The computer uses a set of registers, and memory. Memory is divided into bytes, each byte has its own location number. Big numbers, strings, types and arrays use up multiple bytes. These bytes are stored next to each other. A Long will hold 4 bytes, and will for example occupy locations 239394, 239395, 239396 and 239397. In the computer, these location numbers are called addresses (like the address when sending letters) |
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Pointers hold these location numbers. For bytes, they hold the exact address, for larger objects, it will hold the address of the lowest address (you can determine the other addresses as they will immediately follow the first) |
Pointers hold these location numbers. For bytes, they hold the exact address, for larger objects, it will hold the address of the lowest address (you can determine the other addresses as they will immediately follow the first) |
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Dim mypointer As Long Ptr |
Dim mypointer As Long Ptr |
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</source> |
</source> |
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This one points to the first of |
This one points to the first of 4 bytes of memory, which together form the number. |
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You can not use pointers straight away. Consider sending a letter with no address on it will not do any good. So we must first put an address in there. That leads to the question: how do we get an address. Some things have fixed addresses, like the video card. |
You can not use pointers straight away. Consider sending a letter with no address on it will not do any good. So we must first put an address in there. That leads to the question: how do we get an address. Some things have fixed addresses, like the video card. |
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