#include <stdio.h> int strlen_t(char* s, char t) {     int l;     for(l=0; s[l]!=t && s[l]!='\0'; ++l){}      return l; } int reverse(char* s, char t) {     int l = strlen_t(s, t), i;      for(i=0; i<l/2; ++i)     {         t=s[i];         s[i]=s[l-1-i];         s[l-1-i]=t;     }     return l; } int main() {     char a[200]="Reverse this sentence by word";     int l, lsum;     l = reverse(a, '\0');     for(lsum=0; lsum<l; )     {         lsum+=(reverse(a+lsum,' ')+1);     }     printf("%s\n",a);     return 0; }