c - How to solve uninitialized local variable used? -

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• uninitialized local variable 'j' used 3 answers

#include <stdio.h>  int main() {     int x;  int counter;     while (scanf_s("%d", &x) != 0)     {         puts("enter signed number : ");         if (x % 2 == 0) { counter=counter++; }     }     printf(" %d pair numbers", counter); } 

i get

uninitialized local variable counter used.

the program supposed keep asking numbers until gets 0 , tells amount of pairs given.

the problem facing cause use of variable counter without initializing it. compiler telling you.

when try execute counter=counter++; first time, counter has no definied value. might think int counter; gets initialized 0, wrong in c.

the next problem line counter=counter++; itself. if want increment counter, use counter++. depending on compile using, use of counter=counter++ should give @ least warning. on machine using apple llvm version 8.1.0 (clang-802.0.42) get

warning: multiple unsequenced modifications 'counter' [-wunsequenced]

then try loop until read 0. scanf() (use instead of microsoft specific scanf_s()) not return has read stdin number of input items assigned. returns 0 in event of matching failure.

so here do:

1. initialize counter
2. replace counter=counter++ counter++
3. use loop breaking condition return value of scanf()

one approach following:

#include <stdio.h>  int main() {     int x=0;     int counter=0;      do{         printf("enter signed number: ");         scanf("%d", &x);         if (!(x % 2)){             counter++;         }     } while(x);      printf(" %d pair numbers\n", counter); }