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

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.