In the function second(), the assignment word = “ab”; assigns a new pointer to word, overwriting the pointer obtained through malloc(). When you call free() on the pointer later on, the program crashes because you pass a pointer to free() that has not been obtained through malloc(). Assigning string literals does not have the effect of copying their content as you might have thought. To … Read more
In C language, objects with static storage duration have to be initialized with constant expressions, or with aggregate initializers containing constant expressions. A “large” object is never a constant expression in C, even if the object is declared as const. Moreover, in C language, the term “constant” refers to literal constants (like 1, ‘a’, 0xFF and so on), enum members, and results of … Read more
In the C and C++ programming languages, #pragma once is a non-standard but widely supported preprocessor directive designed to cause the current source file to be included only once in a single compilation. Thus, #pragma once serves the same purpose as #include guards, but with several advantages, including: less code, avoiding name clashes, and improved … Read more
I recently saw this in an answer that was posted for me: What is typedef enum and why should we use it? I googled and found the following: http://www.programiz.com/c-programming/c-enumeration Right now it sounds slightly too technical for me so I dont think I understand what is going on or why one would use that. Bonus (optional): … Read more
Q: uint64_t should have 64 bits width, why the left shift operation overflows?
You are trying to call do_something before you declare it. You need to add a function prototype before your printf line: Or you need to move the function definition above the printf line. You can’t use a function before it is declared.
It should be In C, simple quotes delimit a single character whereas double quotes are for strings.
Why, when printing a number in hexadecimal as an 8 digit number with leading zeros, does %#08X not display the same result as 0x%08X? When I try to use the former, the 08 formatting flag is removed, and it doesn’t work with just 8.
In the function second(), the assignment word = “ab”; assigns a new pointer to word, overwriting the pointer obtained through malloc(). When you call free() on the pointer later on, the program crashes because you pass a pointer to free() that has not been obtained through malloc(). Assigning string literals does not have the effect of copying their content as you might have thought. To … Read more
You are facing issue in because, in the LHS, you’re using an array type, which is not assignable. To elaborate, from C11, chapter §6.5.16 assignment operator shall have a modifiable lvalue as its left operand. and, regarding the modifiable lvalue, from chapter §6.3.2.1 A modifiable lvalue is an lvalue that does not have array type, […] You need to use strcpy() to copy … Read more