The following Bourne shell script and C program can accomplish the same task: read an IP address from user's input and check if the input IP address is valid or not.

Fill in the blanks!

Shell script #!/bin/bash echo -n "Please enter the ip:" _______A._______ echo $ip|grep _______B.______________ if [_______C._______] then echo "Please enter IP address following the IP address pattern" exit fi

#replace the dots in ip with spaces ip=`echo $ip | sed _______D._______ valid=1 n=1 for num in $ip do if [ _______E._______ ] then echo "INVALID: Please enter a number between 0-255 in field $n (index starts from 1 from left)" valid=0 exit fi n=`expr $n + 1` done if [ $valid -eq 1 ];then echo "The ip you entered is valid" fi

C program

#include int main(){ int ip1=0,ip2=0,ip3=0,ip4=0; int n=0; n=scanf("_______A2._________", _______B2.__________); if (n!=4) { printf("Please enter IP address following the IP address pattern"); _______C2._______ } int valid=0; if (ip1<0 || ip1>255) valid = 1; else if (ip2<0 || ip2>255) valid = 2; else if (ip3<0 || ip3>255) valid = 3; else if (_______D2._______) valid = 4; if (_______E2._______) { printf("INVALID: Please enter a number between 0-255 in field %d (index starts from 1 from left) ",valid); }else{ printf("The ip you entered is valid "); } return 0; }