main(){ char st[20],*ps; int i; printf("input a string:\n"); ps=st; scanf("%s",ps); for(i=0;ps[i]!='\0';i++) 这句当中的\0是什么意思? if(ps[i]=='k') { printf("there is a 'k' in the string\n"); break; } if(ps[i]=='\0') printf("There is no 'k' in the string\n"); }