C语言中缀表达式转后缀表达式并利用后缀表达式求值 (小于10)

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#include<stdio.h>

#include<stdlib.h>

int precedence(char c)

{

if(c=='*'||c=='/')

return2;

if(c=='+'||c=='-')

return1;

return0;

}

int main()

{

char stack1[1000];int top_index1=-1;

char stack2[1000];int top_index2=-1;

char c;

while(1)

{

scanf("%c",&c);

if(c=='\n')

break;

elseif(c>='0'&&c<='9')

{

top_index2++;

stack2[top_index2]=c;

}

elseif(c=='(')

{

top_index1++;

stack1[top_index1]=c;

}

elseif(c==')')

{

while(stack1[top_index1]!='(')

{

top_index2++;

stack2[top_index2]=stack1[top_index1];

top_index1--;

}

top_index1--;

}

elseif(c=='+'||c=='-'||c=='*'||c=='/')

{

if(top_index1==-1||precedence(c)>precedence(stack1[top_index1]))

{

top_index1++;

stack1[top_index1]=c;

}

else

{

while(top_index1>=0&&precedence(stack1[top_index1])>=precedence(c))

{

top_index2++;

stack2[top_index2]=stack1[top_index1];

top_index1--;

}

top_index1++;

stack1[top_index1]=c;

}

while(top_index1!=-1)

{

top_index2++;

stack2[top_index2]=stack1[top_index1];

top_index1--;

}

// printf("%s\n",stack2); printf("%d\n",top_index2);

int stack3[1000];int top_index3=-1;

for(int i=0;i<=top_index2;i++)

{

if(stack2[i]>='0'&&stack2[i]<='9')

{

top_index3++;

stack3[top_index3]=stack2[i]-48;

continue;

}

else

{

if(stack2[i]=='+')

{

int t1=stack3[top_index3];

int t2=stack3[top_index3-1];

top_index3--;

stack3[top_index3]=t1+t2;

}

if(stack2[i]=='-')

{

int t1=stack3[top_index3];

int t2=stack3[top_index3-1];

top_index3--;

stack3[top_index3]=t2-t1;

}

if(stack2[i]=='*')

{

int t1=stack3[top_index3];

int t2=stack3[top_index3-1];

top_index3--;

stack3[top_index3]=t1*t2;

}

if(stack2[i]=='/')

{

int t1=stack3[top_index3];

int t2=stack3[top_index3-1];

top_index3--;

stack3[top_index3]=t2/t1;

}

printf("%d",stack3[0]);

}

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