读取字符并校验和

#include<stdio.h>int main(){int line=0;int at_beginning=1;char ch;signed char checksum= -1;while((ch = getchar()) != EOF){if(at_beginning == 1){line += 1;at_beginning = 0;printf("%d ",line);}checksum += ch;putchar(ch);if(ch == '\n'){at_beginning = 1;printf("checksum=%d\n",checksum);}}return 0;}