Answer:
C code is given below
Explanation:
#include<stdio.h>
int main()
{
printf("Input:");
int ch;
int valid=1; // it is set as 1 initially if anything is wrong it is changed to 0
ch=getchar();
if(ch!='#') // it checks if it starts with #
{
valid=0;
}
while((ch = getchar())!= '\n') // this loop runs till line ends
{
if((ch>='a'&&ch<='z')||(ch>='A'&&ch<='Z')||(ch>='0'&&ch<='9')||(ch=='_')) // if conditions are matched then its okay
{
}
else // else valid is changed to 0 from 1
{
valid=0;
}
}
if(valid==0) // if anywhere there is anything wrong then it prints not valid
{
printf("It is not valid hashtag");
}
else // else prints valid
{
printf("It is a valid hastag");
}
}
