foo.c: In function 'main':
foo.c:6:5: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'printf'
    6 |     printf("请输入x1:,x2:");
      |     ^~~~~~
foo.c:7:12: error: 'y1' undeclared (first use in this function); did you mean 'x1'?
    7 |            y1=x1+x2;
      |            ^~
      |            x1
foo.c:7:12: note: each undeclared identifier is reported only once for each function it appears in
foo.c:7:18: error: 'x2' undeclared (first use in this function); did you mean 'x1'?
    7 |            y1=x1+x2;
      |                  ^~
      |                  x1
foo.c:8:12: error: 'y2' undeclared (first use in this function)
    8 |            y2=x1*x2;
      |            ^~
foo.c:9:12: error: 'y3' undeclared (first use in this function)
    9 |            y3=x1%x2;
      |            ^~
foo.c:10:25: error: expected ')' before ';' token
   10 |            printf(("y1");
      |                  ~      ^
      |                         )
foo.c:12:25: error: expected ';' before '}' token
   12 |            printf("y3");
      |                         ^
      |                         ;
   13 | }
      | ~                        

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