Expression preceding parentheses?
The error is referring to this line: Here you’re (apparently) trying to call delay as a function. However, delay is declared as: It’s just a number, not a function, hence you can’t call it.
c
How to initialize a struct in accordance with C programming language standards
In (ANSI) C99, you can use a designated initializer to initialize a structure: Other members are initialized as zero: “Omitted field members are implicitly initialized the same as objects that have static storage duration.” (https://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html)
Reading a string with scanf
An array “decays” into a pointer to its first element, so scanf(“%s”, string) is equivalent to scanf(“%s”, &string[0]). On the other hand, scanf(“%s”, &string) passes a pointer-to-char[256], but it points to the same place. Then scanf, when processing the tail of its argument list, will try to pull out a char *. That’s the Right Thing when you’ve passed in string or &string[0], but when … Read more
What’s the equivalent of new/delete of C++ in C?
There’s no new/delete expression in C. The closest equivalent are the malloc and free functions, if you ignore the constructors/destructors and type safety.
where does stdio.o live in linux machine?
I’d suggest that you run gcc -v your_file.c. That will let you see exactly what commands your linker is using. You probably don’t have an stdio.o file to link against. Instead this is included in the C runtime library and the exact file will depend on your system configuration.
Why am I getting “undefined reference to sqrt” error even though I inclu de math.h header?
The math library must be linked in when building the executable. How to do this varies by environment, but in Linux/Unix, just add -lm to the command: The math library is named libm.so, and the -l command option assumes a lib prefix and .a or .so suffix
Invalid pointer error on invoking free() after malloc in C
I am doing very basic dynamic allocation practice in C and I came across this issue: when I am trying to call free() with the pointer returned by malloc(), I am getting Invalid pointer error during run time. When I remove free() from code, it works fine. The pointer that I am using is not modified anyhow after returned by malloc (except … Read more
How do you pass a function as a parameter in C?
Declaration A prototype for a function which takes a function parameter looks like the following: This states that the parameter f will be a pointer to a function which has a void return type and which takes a single int parameter. The following function (print) is an example of a function which could be passed to func as a parameter because it is … Read more
how to convert negative hexadecimal to decimal
without using a computer you can calculate it like this: 0xFFFF FE58 is a negative number in 2’s complement. To get the absolute value you have to invert all bits and add 1 in binary. You also can subtract this number from the first number out of range (0x1 0000 0000) now we know that your … Read more
#31 expression must have integral type
I’m having some problems with my C code and get the error in the title. First off, Uint16 is defined as: I use two variables in the function where I get the error, they are defined as: I call the function like this: and the function definition is like this: and lastly, the declaration in … Read more