Malloc function (dynamic memory allocation) resulting in an error when it is used globally

Question

#include
#include
char *y;
y=(char *)malloc(40); // gives an error here
int main()
{
    strcpy(y,\"hello world\");
}

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Answer 1

You cannot use a function call when initializing a static or global variable. In the following code sequence, we declare a static variable and then attempt to initialize it using malloc:

static int *pi = malloc(sizeof(int));

This will generate a compile-time error message. The same thing happens with global variables but can be avoided for static variables by using a separate statement to allocate memory to the variable as follows. We cannot use a separate assignment statement with global variables because global variables are declared outside of a function and executable code, such as the assignment statement, must be inside of a function: static int *pi; pi = malloc(sizeof(int));

From the compiler standpoint, there is a difference between using the initialization operator, =, and using the assignment operator, =.