├── README.md
└── calculator.c


/README.md:
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  1 | # calculator
  2 | 编译原理课程作业-- 计算器， 内含表达式的计算（中缀转后缀）
  3 | 
  4 | ### 计算器接受四则运算表达式为输入。如果表达式语法正确，则输出计算结果，否则报错，指出错误位置及原因。 
  5 | #### 测试用例：
  6 | 1.正常运行
  7 | ``` C
  8 | float a; 
  9 | int b; 
 10 | a = (10.44*356+1.28) / 2 + 1024 * 1.6;
 11 | b = a * 2 - a/2;
 12 | write(b);
 13 | write(a).
 14 | ```
 15 | 
 16 | 2. Error( line 4 ): undefined identifier
 17 | ``` C
 18 | float a; 
 19 | int b; 
 20 | a = (10.44*356+1.28) / 2 + 1024 * 1.6;
 21 | b = a * 2 - c/2;
 22 | write(b).
 23 | ```
 24 | 
 25 | 3. Error( line 2 ): syntax error
 26 | ``` C
 27 | float a; 
 28 | int ; 
 29 | a = (10.44*356+1.28) / 2 + 1024 * 1.6;
 30 | b = a * 2 - a/2;
 31 | write(b);
 32 | write(a).
 33 | ```
 34 | 
 35 | 4. Error( line 4 ): divide by zero
 36 | ``` C
 37 | float a; 
 38 | float b; 
 39 | a = 10.44;
 40 | b = a/0;
 41 | write(b);
 42 | write(a).
 43 | ```
 44 | 
 45 | 5. Error( line 4 ): type cast : turn int into float
 46 | ``` C
 47 | int a; 
 48 | float b; 
 49 | a = 10.44;
 50 | b = a;
 51 | write(b);
 52 | write(a).
 53 | ```
 54 | 
 55 | 6. Error( line 3 ): uninitialized identifier
 56 | ``` C
 57 | float a; 
 58 | int b; 
 59 | b = a * 2 - a/2;
 60 | write(b);
 61 | ```
 62 | 
 63 | ### 语法描述
 64 | ```
 65 | <程序> ->
 66 | (<语句><行结束符号>)*(<语句><全文结束符号>)
 67 | 
 68 | <语句> -> 
 69 | <声明语句>|<赋值语句>|<输出语句>
 70 | 
 71 | <声明语句> -> 
 72 | <声明符号><空格> <变量名>
 73 | 
 74 | <赋值语句> -> 
 75 | <变量名><等号><表达式>
 76 | 
 77 | <输出语句> -> 
 78 | <输出函数>(<变量名>)
 79 | 
 80 | <声明符号> -> float | int
 81 | 
 82 | Digit -> [0-9];
 83 | Letter ->[a-zA-Z]
 84 | <变量名> -> (_|Letter)(Letter | Digit|_)*
 85 | 
 86 | <行结束符号> -> ;
 87 | 
 88 | <全文结束符号> ->.
 89 | 
 90 | <等号> -> =
 91 | 
 92 | <输出函数> -> write
 93 | 
 94 | <空格> -> ( )+
 95 | 
 96 | <表达式> ->(<运算符号>|<整数>|<浮点数>)*
 97 | 
 98 | <运算符号> ->[+-*/()]
 99 | 
100 | <整数> -> Digit*
101 | 
102 | <浮点数> -> (Digit+).(Digit*)
103 | 
104 | ```
105 | 
106 | 


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/calculator.c:
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https://raw.githubusercontent.com/WanDerer23333/calculator-compiler/96adbff616eeeb0009cc9e05a51182c7df8f8bd5/calculator.c


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