Find all even numbers in given range with C programming

#include<stdio.h>
void main(){
	int a, b;
	char c;
	printf("Enter a smaller number: ");
	fflush(stdin);
	scanf("%d", &a);
	printf("Enter a bigger number: ");
	fflush(stdin);
	scanf("%d", &b);
	if(a > b){
		printf("%d is not smaller than %d\n", a, b);
		return;
	}

	c = 0;
	do{
		if(0 == b%2){
			if(!c){
				printf("All even numbers: ");
			}
			printf("%c%d",c,b);
			c = ',';
		}
		b--;
	}while(a <= b);
	printf("\n");
	if(!c){
		printf("No even numbers found\n");
	}
}

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