strlen code not working

Question

Working on this little piece of code, but for some reason it keep crashing the whole time.

Anyone got an idea what i'm doing wrong

char *str;
printf("Enter a string\n");
gets(str);
printf("The size of the string is %d", strlen(str));
system("PAUSE");    
return 0;

Answer 1

You have not allocated any memory for str. Declare a buffer, for example char str[50], but be aware of buffer overflows.

Answer 2

You only created an char* pointer which points to random space in memory and you try to do something with it - and that is why your program crashes.

You should create an array of chars:

char str[50];

or dynamically allocate memory for string with malloc:

char* str;
str = (char *)malloc(50*sizeof(char)); // allocate memory
// some operations
free(str);                      // deallocate memory

where 50 is your estimated size of buffer.