When a function requires a pointer as an argument, what it really needs is an address. To pass a pointer to a function, you can use a pointer variable or use the ampersand operator to pass the address of any variable. Within the function, a pointer, or address, passed is treated as a pointer: it's a memory location or, with the asterisk operator, it's the value at that location. By passing pointers to a function, your code can manipulate values directly without having to return them.
- When you pass a pointer to a function … you're passing its address, the memory location … stored in the pointer. So a function … that accepts a pointer is an argument. … Accepts a variable's address in memory. … In this exercise files, integer variable A … is initialized to two at line ten. … Its address is passed to the doubler function … in line 13. You see the ampersand … address of operator. And then, in the function, … no value is returned. But within the function, … the value at the address is doubled. Build and run. … And the value is modified without being returned. … That's because the doubler function … is able to modify the value indirectly … through its address. In this code, … pointer A is passed directly to the doubler … function at line 15. No ampersand … is needed 'cause it's a pointer. … Pointers must be initialized before they're used. … So variable A is assigned to the address … of variable B in line 13. Build and run. … And the value is doubled. … Passing pointers is one way you can return …
Author
Dan Gookin
Released
5/1/2019- Working with arrays
- Building a structure
- Creating an array of structures
- Testing characters
- Working with strings in C
- Using pointers to manipulate data
- Manipulating files
- Using command-line arguments
- Working with time functions
Skill Level Intermediate
Duration
Views
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Introduction
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Using the exercise files1m 23s
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Configuring the IDE2m 34s
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1. Arrays and Structures
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Understanding arrays2m 59s
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Working with arrays3m 5s
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Modifying arrays3m 11s
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Building a structure3m 23s
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Nesting structures2m 56s
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Understanding a union2m 47s
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2. Characters and Strings
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Testing characters2m 34s
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Fetching string input3m 18s
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Sending string output2m 46s
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Using printf() placeholders3m 36s
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Exploring string functions3m 29s
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Manipulating strings3m 53s
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Avoiding string problems2m 27s
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3. Pointers
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Understanding pointers3m 19s
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Doing pointer math2m 57s
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Allocating storage3m 15s
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Working with a pointer array3m 38s
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Using pointers in structures3m 30s
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Returning pointers2m 39s
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4. Files and the Operating System
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Reading from a file3m 25s
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Writing to a file3m 24s
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Working with raw data2m 53s
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Using random file access2m 47s
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Manipulating files2m 57s
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Exploring the path2m 8s
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Reading a directory2m 53s
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Getting file information2m 46s
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Using command line arguments2m 44s
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Calling the operating system2m 46s
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5. The Interesting and Extraordinary
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Solving math puzzles3m 32s
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Creating random numbers3m 42s
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Working with time functions3m 54s
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Sorting data4m 8s
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Using a debugger4m 53s
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Writing your own header file2m 53s
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Challenge: Lotto simulation1m 18s
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Solution: Lotto simulation2m 29s
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Conclusion
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Next steps1m 52s
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Video: Passing pointers to functions