The summary of ‘What are double pointers in C?’

The video discusses the concept of double pointers in C programming, emphasizing the ability to manipulate the values that pointers are pointing to. By dereferencing double pointers, it becomes possible to change the value being referenced across functions. The speaker demonstrates how double pointers offer flexibility in updating the values pointed to. Additionally, the video explains the challenges of obtaining the address of variables in C programming using pointers and clarifies the correct method to retrieve multiple levels of addresses. The demonstration includes visuals to illustrate memory storage and the dereferencing process. Overall, the video highlights the importance and usefulness of double pointers in C programming for efficient memory management and value manipulation.

00:00:00

In this segment of the video, the speaker explains what a double pointer is using a simple string stored in the global memory. They introduce a function called `display` that takes a double pointer to a char. The function prints the output that is passed in. The concept of dereferencing a double pointer is emphasized, showing how the address of a string is stored and accessed in memory. The demonstration uses visuals of memory storage to illustrate how double pointers work in C programming.

00:03:00

In this segment of the video, the speaker explains the concept of double pointers using a memory block example. They demonstrate how output is a pointer to STR, which itself is a pointer to a string. The speaker clarifies that STR is a pointer to a char, making it a char pointer. This leads to output being a pointer to a char pointer, termed a double pointer. They emphasize that having a double pointer allows for the manipulation of the pointer being pointed to, enabling flexibility in changing values.

00:06:00

In this segment of the video, the speaker discusses the concept of double pointers in C programming. By dereferencing a double pointer, you can change the value that the pointer is pointing to, even across functions. The speaker demonstrates how by using a double pointer, they are able to change the value the pointer is pointing to effectively. Double pointers are useful when you want to modify a pointer’s value in a different function. The example shows how a double pointer can be used to change the value that the original pointer references, allowing it to point to a different location in memory. The speaker also mentions that technically, you can have a pointer to a pointer to a pointer, and so on, although this practice may be complex and usually unnecessary.

00:09:00

In this segment of the video, the speaker discusses the challenge of obtaining the address of a variable in C programming using pointers. The speaker explains that simply adding “get address of” multiple times does not work as expected. This is because operators work in a way that retrieving the address of a variable multiple times results in only obtaining the value, not the address. The speaker emphasizes that values in a program do not intrinsically have addresses and trying to get the address of the address of a value is not feasible. To properly obtain multiple levels of addresses, the speaker suggests creating each pointer one after the other instead of attempting to chain the “get address of” operator.

00:12:00

In this segment of the video, the speaker explains the concept of double pointers. They demonstrate how dereferencing a double pointer twice would lead to accessing the first character of a string. They also mention that you can dereference a double pointer as many times as you have pointers. The speaker concludes by highlighting the ability to dereference pointers multiple times based on their level (e.g., a simple pointer once, double pointer twice).