缓冲输出的小问题

#include <stdio.h>

int main(void)
{
    int c = 0;
    
    static char buf[1];
    setbuf(stdout, buf);

    while(c != EOF) {
        printf("start\n");
        c = getchar();
        putchar(c);
        printf("end\n");
    }   
    return 0;
}

// 为什么不管输入什么  都不输出？

c
[解决办法]

void setbuf ( FILE * stream, char * buffer );

buffer
User allocated buffer. Shall be at least BUFSIZ bytes long. Alternatively, a null pointer can be specified to disable buffering