Write function in C language, realize strlen function of calculating string length

This article describes three ways to:

1. Cyclic counting method, (set a counter).

2. Recursive method (function call itself for calculation)

3. Pointer-pointer method (this method is used by the library function)

Now included in the procedure:

Method 1:

/* Count Method */int My_strlen (char *p) {int number = 0;while (*p) {number++;p + +;} return number;}

Method 2:

/* Recursive */int My_strlen (char *str1) {if (*str1! = ') ') {Str1++;return 1 + my_strlen (STR1);} Elsereturn 0;}

Method 3:

/* Pointer subtraction */int my_strlen (char *p) {char *pstart = p;while (*p) P++;return P-pstart;}

Now give the main function a call and test:

int main () {char *str = "ASDFG"; int len = My_strlen (str);p rintf ("%d\n", Len); System ("pause"); return 0;}

The results are 5 and the results are correct!

If any of the great gods find that the procedure has yet to be improved, please criticize it!

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Write function in C language, realize strlen function of calculating string length