c - Present error messages for invalid data entry -

this first project (kind of text based game). how present error messages when text entered in area numbers prompted , vice versa. or possibly ability reject improper input altogether.

#include <stdio.h> #include <stdlib.h>  int main() {     char name[20];     char q1;     int q2[2],q3[2];     float qt[3];     for(q1='n';q1!='y';)     {         printf("what name?\n");         gets(name);         printf("you have entered: ");         puts(name);         printf("is okay? [y/n]\n");         scanf("%s",&q1);         if(q1!='y'&&q1!='n')             printf("user error: '%c' not recognized.\nplease enter 'y'         continue or 'n' edit name\n",&q1);         if(q1!='y'&&q1!='n')             scanf("%s",&q1);     }     printf("okay, %s.",name);     printf(" out of 3 choices most?\n1.      start garden.\n2. build house.\n3. travel somewhere you've never been.\n");     scanf("%d",q2);     (;q2[0]>3||q2[0]<1;)     {         printf("user error: '%c' not recognized.\nplease enter 1 of    options given.",q2);         scanf("%d",q2);     }     if(q2[0]==1)         printf("what plant in garden?\n1. flowers\n2. vegetables\n3. fruit , berries\n");     else         if(q2[0]==2)             printf("where build house?\n1. in mountains\n2. in desert\n3. sea\n");         else             if(q2[0]==3)                 printf("what bring such place?\n1. new faces , cultures\n2. treasures , adventure\n3. escape ordinary\n");             else                 for(;q2[0]>3||q2[0]<1;)                 {                     printf("user error: '%c' not recognized.\nplease enter 1 of options given.",&q2);                     scanf("%d",q3);                 }     scanf("%d",q3);     qt[0]=(q2[0]*12)/q3[0];     printf("%f",qt[0]);     return 0; }