Can memcpy given value as source address in c

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WebJan 7, 2016 · memcpy () is used to copy a block of memory from a location to another. It is declared in string.h // Copies "numBytes" bytes from address "from" to address "to" void * memcpy (void *to, const void *from, size_t numBytes); Below is a sample C program to … Before memset(): GeeksForGeeks is for programming geeks. After memset(): … WebNov 27, 2024 · No, you can't [portably] use memset for that purpose, unless the desired target value is 0.memset treats the target memory region as an array of bytes, not an array of ints.. A fairly popular hack for filling a memory region with a repetitive pattern is actually based on memcpy.It critically relies on the expectation that memcpy copies data in …

c++ - Using `memcpy()` to assign a pointer an address

WebMar 12, 2013 · you can use memcpy as, memcpy(&req_byte, (buf+4), 1); this will copy fifth byte of your message to req_byte. you can vary number after (+) in source buffer to … WebApr 29, 2004 · Optimizing Memcpy improves speed. Knowing a few details about your system-memory size, cache type, and bus width can pay big dividends in higher performance. The memcpy () routine in every C … gram of carb calorie

c++ - How to get float address for use with memcpy? - Stack Overflow

WebJan 21, 2016 · Define you own memcpy to copy to this address space : void my_memcpy( ptr8 addr_dest, const void * src, int len ) { memcpy( my_destination_memory + … WebJun 4, 2013 · I need a function that stores data into a void pointer. Here is a simple example of it: void saveData (void* data) { char inputData [] = "some data"; memcpy ( (char*)data, inputData, sizeof (inputData)); } However I get segmentation errors when I do this, even though it compiles just fine. My function argument has to be a void pointer because I ... WebJan 22, 2024 · Some (most) implementations of memcpy() assume that it can copy data in one specific direction which will cause data to be corrupted if areas overlap in the wrong way (e.g. if the implementation uses the "lowest address first" direction and the destination area overlaps and is at a higher address than the source, then writes to the destination ... gram of dab

Garbage value using memcpy() in c - Stack Overflow

c - memcpy and pointers - Stack Overflow

WebApr 17, 2012 · I am trying to read two integers, stored consecutively, from a memory block (i have a pointer void *block pointing to the contents of the block) using memcpy. The first one is read just fine using: memcpy (&test, block, sizeof (int)); I try to read the second using: memcpy (&test, block + sizeof (int), sizeof (int)); (Of course i am having ... WebApr 1, 2011 · I am trying to write a stl vector in C, and I could do it if client allocating memory on the heap and pass as an element to me. But I want it to work with basic datatype and there should not be special way to pass variables on the stack or heap variables. – Avinash Apr 5, 2011 at 13:33 gram of dmt costWebJun 24, 2015 · no, it's like *ptr = value;. memcpy takes the address of both source and destination. value must have type char * and ptr have type char ** (although you could … china the wrestler that died

"WebDec 11, 2010 · In general, memcpy is implemented in a simple (but fast) manner. Simplistically, it just loops over the data (in order), copying from one location to the other. … " - Can memcpy given value as source address in c

Can memcpy given value as source address in c

c - Using memcpy with hex values - Stack Overflow

WebOct 2, 2024 · memcpy only copies from the beginning of an array if that's what address you pass it. The name of an array a is synonymous with the address of the first element &a [0], so if you do memcpy (dest, src, size), then the copy will be from the start of the array src. WebMay 28, 2009 · which is actually just the reverse of the memcpy () you did to get the pointer there in the first place. Although, treating the pointer as an int: int addressOfArgTwo = (unsigned int)buff; is also dangerous, if you're moving between 32-bit and 64-bit architectures, as Michael pointed out. Pointers aren't always 32-bit integers.

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WebSo the answer is no; the check is not necessary (or yes; you can pass zero). Share Improve this answer Follow edited Sep 22, 2012 at 10:42 answered Sep 20, 2010 at 13:32 Mike Seymour 248k 28 442 637 1 Would a pointer be considered "valid" for purposes of such a function if it pointed to the location following the last element of an array? WebAug 3, 2015 · @PSkocik "Character type" is a term-of-art in the C standard which encompasses both single char objects and arrays of them (and probably some other stuff I don't remember off the top of my head). Regardless, the point is that char[4] and int are not compatible types and therefore you cannot use int* to access memory declared as …

WebOct 11, 2024 · When you refer to the address of a pointer, this normally means the pointer's own location in memory, not the value it holds (which also is an address). – Andreas Wenzel Oct 11, 2024 at 4:55 1 @N001: If you follow the advice I gave in my first comment, does your program then work as intended? Both printed pointer values are the same, then. WebOct 3, 2024 · 2 Answers. Sorted by: 5. It's how memcpy works: it takes a pointer to data it will copy. Your data is pointer to float, so you need to pass pointer to pointer to float: #include int main () { float f = 20.0f; float* pf = &f; char data [sizeof (pf)]; memcpy (data, &pf, sizeof (data)); } Share.

WebMar 28, 2013 · As a basic type safety check it makes sure the sizes of source and destination elements are the same. That's evaluated at compilation time as well. … WebNov 20, 2014 · If you have allocated using malloc you must state the size of the array. int * src = malloc (ARRAY_LENGTH*sizeof (*src)); int * dst1 = malloc …

WebJul 11, 2013 · Understanding the source code of memcpy () 00018 void *memcpy (void *dst, const void *src, size_t len) 00019 { 00020 size_t i; 00021 00022 /* 00023 * memcpy …

WebOct 21, 2014 · But memcpy () is about copying memory objects, not values. An object resides at a given address, and contains a given value. Taking n gives the value, … gram of diamond waxWebOct 25, 2015 · Save it to a .c file, like test.c, and compile it using gcc, like this: It will (most likely) behave differently. Try replacing memcpy with strncpy and see what happen. I hope the example is useful. With memcpy, the destination cannot overlap the source at all. With memmove it can. china thick puzzle exerciseWebApr 8, 2024 · You can certainly use memcpy (c1->ques, q1->ques, string_size). But it's non-standard for a string copy operation and reduces readability. – selbie Apr 8, 2024 at 3:35 Add a comment 1 In C parameters are passed by value rather than by reference. china thickness tester supplierWebApr 28, 2011 · If you have larger chunk of data to store, use memcpy or memmove with that address to copy data from/to it, like this: #include int main () { const char data … gram of dabs priceWebFeb 16, 2013 · As such, it has no address which could be given as parameter to memcpy or another function that expects a memory location. If you want to do this, you need to have a real constant (such as const int ), as suggested in the other answers. china thigh kick padsWebApr 8, 2024 · Also remember that argument in C are passed by value, meaning the value is copied into the argument variable. Modifying the argument variable (like assigning to it) … china thickness tester suppliersWebNov 3, 2012 · First, memcpy () doesn't succeed or fail in the normal sense. It just copies the data, which might cause a fault/exception if it reads outside the source array or writes outside the destination array, and it might also read or write outside one of those arrays without causing any fault/exception and just silently corrupting data. china thigh kick pads supplier