Find string length using strlen and a function. print with empty string

Question

So I am writing this code to print string length of any string I input and I basically have the code already working but I am having trouble because when I enter a blank string my program doesn't print to screen correctly. It works with a space(spacebar) and all other strings but I must be able to enter an empty string. we are supposed to use something like: buf[strlen(buf) - 1] = '\0'; to enter and print empty strings, but I am not sure how to enter it in the code correctly. Any ideas??

here is my program:

#include<stdio.h>
#include<conio.h>
#include<string.h>

int *MyStrlen(const char *string2);

int main()
{
char string2[100];

printf("Enter a string: \n");
scanf("%100[^\n]",&string2);

int  length, length2;

length =  strlen(string2);
length2 = MyStrlen(string2);

printf("strlen(''%s'') returned %d\n", &string2, length);
printf("MyStrlen(''%s'') returned %d\n", &string2, length2);

return 0;
}

also, here is MyStrlen function, All works correctly besides entering empty string.

int *MyStrlen(const char *string2)
{
int stringcount=0;

while (string2[stringcount]!='\0')
{
    stringcount++;
}
return stringcount;
}

Answer 1

Maybe the problem could be corrected with:

Initilize the first element of string2 to '\0' before the scanf:

string2[0] = '\0';

Change the return type of int *MyStrlen(...) to int:

int MyStrlen(const char *string2);

As this post: How to input a string using scanf in c including whitespaces, a safer way is to specify a size 1 less than the size of string2 buffer:

scanf("%99[^\r\n]", &string2[0]);

Check out the scanf man page for more information.

The code:

#include<stdio.h>
#include<conio.h>
#include<string.h>

int MyStrlen(const char *string2);

// change the return type to int
int MyStrlen(const char *string2)
{
    int stringcount=0;

    while (string2[stringcount] != '\0')
        stringcount++;
    return stringcount;
}
int main()
{
    char string2[100];

    // Initialize the first element to 0
    string2[0] = '\0';
    printf("Enter a string: \n");

    scanf("%99[^\r\n]", &string2[0]);

    int  length, length2;


    length =  strlen(string2);
    length2 = MyStrlen(string2);

    // Change to &string2 to string2
    printf("strlen(''%s'') returned %d\n", string2, length);
    printf("MyStrlen(''%s'') returned %d\n", string2, length2);

    return 0;
}

The output with empty string:

Enter a string:

strlen('''') returned 0
MyStrlen('''') returned 0

The output with "aaa":

Enter a string:
aaa
strlen(''aaa'') returned 3
MyStrlen(''aaa'') returned 3

Answer 2

Well, the problem is with

scanf("%100[^\n]",&string2);

Change it to

fgets (string2, 100, stdin);

Because that scanf cannot read a blank string.

Also, as mentioned in @M.M's comment, check for '\n':

int last = strlen (string2) -1;
if (string2 [last] = '\n') {
   string2 [last] = '\0';
}

In the second case I entered a blank string.

The completely corrected code:

#include<stdio.h>
#include<conio.h>
#include<string.h>

int *MyStrlen(const char *string2);

// change the rerturn type to int
int *MyStrlen(const char *string2)
{
    int stringcount=0;

    while (string2[stringcount] != '\0')
        stringcount++;
    return stringcount;
}
int main()
{
    char string2[100];

    // Initialize the first element to 0
    string2[0] = '\0';
    printf("Enter a string: \n");
    fgets (string2, 100, stdin);
    int  length, length2;
    int last = strlen (string2) -1;
    if (string2 [last] = '\n') {
       string2 [last] = '\0';
    }


    length =  strlen(string2);
    length2 = MyStrlen(string2);

    printf("strlen(''%s'') returned %d\n", string2, length);
    printf("MyStrlen(''%s'') returned %d\n", string2, length2);

    return 0;
}

---

Also as mentioned in @Gomiero's answer, initialize your string to \0.