表达式求值(浮点型).docx

#include #include #include #include #define max 100#define Elemtype floattypedef struct char *data;int top;int stacksize;seqstack;typedef struct Elemtype *data1;int top;int stacksize;seqstack1;int prior(char str1,char str2);/字符栈int initstack(seqstack &L)L.data=(char *)malloc(max * sizeof(char);if(L.data=NULL)printf(内存分配失败!n); exit(0);L.top=-1;L.stacksize=max;return 1;int pushstack(seqstack &L,char ch)if(L.top=L.stacksize-1)printf(栈满!n); return 0;L.top+;L.dataL.top=ch;return 1;char popstack(seqstack &L)if(L.top=-1)printf(空栈!n);elsereturn L.dataL.top-;char gettop(seqstack L)if(L.top=-1)printf( 空栈!n);elsereturn L.dataL.top;/求值栈int initstack1(seqstack1 &L1)L1.data1=(Elemtype *)malloc(max * sizeof(Elemtype);if(L1.data1=NULL)printf(内存分配失败!n); exit(0);L1.top=-1;L1.stacksize=max;return 1;int pushstack1(seqstack1 &L1,Elemtype x)if(L1.top=L1.stacksize-1)printf(栈满!n); return 0;L1.top+;L1.data1L1.top=x;return 1;float popstack1(seqstack1 &L1) float n;if(L1.top=-1) printf(空栈!n); elsen=L1.data1L1.top-;return n;/优先级比较int prior(char str1,char str2)switch(str1)case (:case #: return 0;case +:case -:switch(str2) case #:case +:case -: return 1; case *:case /: return 0; break;case *:case /:return 1;/计算float calculate(float a,float b,char ch)if(ch=*)return (a*b);else if(ch=/)return (a/b);else if(ch=+)return (a+b);else return (a-b);/字符转换为实数float transform(char *ch)int i=0,k=0,j;float n,n2=0,n1=0;char str10;while(chi=0& chi=0& ch=9| ch=.)return 1;elsereturn 0;/转为后缀表达式 void Tosuffix(char *p,char *suffix)int i=0,j=0;seqstack L;char ch;initstack(L);pushstack(L,#);while(pi!=#)if(indigt(pi)suffixj+=pi;else switch(pi) case (:pushstack(L,pi);break; case ): ch=popstack(L); while(ch!=() suffixj+=ch; ch=popstack(L); break; default:suffixj+= ; /遇运算符读一个空格，使运算符前后数字字符隔开ch=gettop(L);while(prior(ch,pi)suffixj+=ch; ch=popstack(L); ch=gettop(L);pushstack(L,pi);break; i+;while(L.top!=0) /扫描完输入表达式后，栈中还有运算符 ch=popstack(L);suffixj+=ch; suffixj=0;/有后缀表达式求值 float result_(char *suffix) float result1,result2,result,n;int i=0,j=0,k,N;N=strlen(suffix);char str10;seqstack1 L1;initstack1(L1);while(suffixi) if(indigt(suffixi)while(indigt(suffixi) strj+=suffixi; i+; strj=0;j=0;n=transform(str);pushstack1(L1,n);i-; /防止跳过字符 else if(suffixi= ) for(k=i;kN;k+) suffixk=suffixk+1; N=N-1; i-; /防止跳过字符 else result1=popstack1(L1); result2=popstack1(L1); result=calculate(result2,result1,suffixi); pushstack1(L1,result); i+; return result; int main() char *p,*suffix; int i; p=(char *)malloc(max * sizeof(char); suffix=(char *)malloc(max * sizeof(char); printf(输入表达式（以#号结束）:); scanf(%s,p); i=strlen(p); i-; if(pi!=#)