C cast literal char '0' to int 0 (zero), how?

问题

How would I go to cast/convert literal char '0' to int 0?

i.e.:

char string[] = "0101";
char ch = string[0];
x = magic(ch);
if (x)
    printf("int zero")

回答1:

ch = 0;

Now, if you want to convert any digit-character to its numeric equivalent, you'd need something like:

ch = ch - '0';

来源：https://stackoverflow.com/questions/41365518/c-cast-literal-char-0-to-int-0-zero-how