/in/P3.c: In function 'main':
/in/P3.c:15:31: warning: unused variable 'ai' [-Wunused-variable]
     int a,b,flag=0,len,jiahao,ai;char str[256]={0},str1[256]={0},stra[256]={0},strb[256]={0};
                               ^~
/in/P3.c:27:62: warning: 'b' may be used uninitialized in this function [-Wmaybe-uninitialized]
     if((a==0&&isprime(b))||(b==0&&isprime(a))||(isprime(a*a+b*b)))
                                                             ~^~
/in/P3.c:27:58: warning: 'a' may be used uninitialized in this function [-Wmaybe-uninitialized]
     if((a==0&&isprime(b))||(b==0&&isprime(a))||(isprime(a*a+b*b)))
                                                         ~^~
/in/P3.c:25:55: warning: 'jiahao' may be used uninitialized in this function [-Wmaybe-uninitialized]
         else if(str1[i]=='i'){strncpy(strb,str1+jiahao+1,i-jiahao-1);b=atoi(strb);}
                                                       ^