iOS Basics Getting Started--malloc method

char m;

scanf ("%c", &m); // preceded by a space to remove the space, carriage return and other operations

NSLog (@ "The character is%c", m);

Above this program is you are more familiar with the two methods an input, an output, but if I change to change to

Char *m;

NSLog (@ "\ n Please enter a character ");

scanf ("%c", M);

NSLog (@ "\nthis is%c", *m);

Is it correct to compile with an error and will the runtime have problems?

In fact, this program, if the compiler does not occur when the exception, but if run, there will be a run-time exception (the LLDB command, the end of the Kill command), because we have defined a char pointer m, the pointer is not initialized assignment, Causes the program to run without finding the memory space to store the character, if changed to

Char *m;

m= (char *) malloc (sizeof(char)); malloc () dynamically allocates memory , allocates the first address of memory with malloc, and assigns a value to m

NSLog (@ "\ n Please enter a character ");

scanf ("%c", M);

NSLog (@ "\nthis is%c", *m);

      if the malloc method is used to allocate space, the program can proceed normally, and the sizeof method gets the space size of the corresponding type

When it is hot again, because we use malloc to dynamically allocate space, we can use a char pointer to output a string, as follows:

Char *a;

A= (Char *)malloc(sizeof(char) *); // Dynamic Allocation - a continuous Char memory Address

NSLog (@ "\ n Please enter a string ");

scanf ("%s", a);

NSLog (@ "\nthis is%s", a);

iOS Basics Getting Started--malloc method