Reverse words from the user inputted string, e.g. Input: Hello world Output: world Hello

reverse-words.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

char* strev(char str[])
{
  int i,j;
  char temp[100];
  i = 0;
   j = strlen(str) - 1;

   while (i < j) {
      temp[1] = str[i];
      str[i] = str[j];
      str[j] = temp[1];
      i++;
      j--;
   }
  return str;
}

int main()
{
    char a[1000],temp[1000],*rev_a,reverse[1000]="",buffer[500];
    int j,len,i,testcase,tc=1,ch;
    //fflush(stdin);
    
    scanf("%d",&testcase);
    while ((ch = getchar()) != '\n' && ch != EOF);
    //fflush(stdin);
while(tc <= testcase)
{
    sprintf(buffer, "Case #%d: ",tc);
    strcat(reverse,buffer);

    fgets(a,100,stdin);

    rev_a = strev(a);

    len = strlen(a);
    j=0; //result = NULL;
    for(i=0;i<len;i++)
    {
        for(j=0; i<len && rev_a[i]!=' ' && rev_a[i]!='\n'; ++i,++j)
        {
            temp[j] = rev_a[i];
        }
        temp[j] = '\0';
        strcat(reverse, strev(temp));
      	if(i>1 && i<len)
        strcat(reverse, " ");
    }
    strcat(reverse,"\n");
tc++;
}

    printf("%s",reverse);
    return 0;
}