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  1. #include <stdio.h>
  2. #include <stdlib.h>
  3. #include <string.h>
  4. #include <ctype.h>
  5.  
  6. int main() {
  7.   char* src = "1 2 + 4 5 + * 3 /";
  8.  
  9.   int ns[256];
  10.   int ni;
  11.  
  12.   char cs[16];
  13.   int ci;
  14.  
  15.   int i;
  16.   char c;
  17.   int l;
  18.  
  19.   int n1;
  20.   int n2;
  21.  
  22.   ni = 0;
  23.   ci = 0;
  24.   l = strlen(src);
  25.   for (i = 0; i < l; i++) {
  26.     c = src[i];
  27.     if (c == ' ') {
  28.       if (ci > 0) {
  29.         cs[ci] = '\0';
  30.         ns[ni++] = atoi(cs);
  31.         ci = 0;
  32.       }
  33.     } else if (isdigit(c)) {
  34.       cs[ci++] = c;
  35.     } else if (c == '+') {
  36.       n2 = ns[--ni];
  37.       n1 = ns[--ni];
  38.       ns[ni++] = n1 + n2;
  39.     } else if (c == '-') {
  40.       n2 = ns[--ni];
  41.       n1 = ns[--ni];
  42.       ns[ni++] = n1 - n2;
  43.     } else if (c == '*') {
  44.       n2 = ns[--ni];
  45.       n1 = ns[--ni];
  46.       ns[ni++] = n1 * n2;
  47.     } else if (c == '/') {
  48.       n2 = ns[--ni];
  49.       n1 = ns[--ni];
  50.       ns[ni++] = n1 / n2;
  51.     }
  52.   }
  53.  
  54.   printf("expression %s\n", src);
  55.   if (ni > 0) {
  56.     printf("result %d\n", ns[--ni]);
  57.   } else {
  58.     printf("result %s\n", src);
  59.   }
  60.  
  61.   return 0;
  62. }
Success #stdin #stdout 0s 2292KB
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stdin
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Standard input is empty
stdout
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expression 1 2 + 4 5 + * 3 /
result 9
https://ideone.com/ffiI9h
language:
C (gcc 8.3)
created:
11 years ago
visibility:
public

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