c - 循环中的数组元素返回随机大数字(有时为负数)

Question

我正在扫描输入文件中的字符并尝试打印它们在输出文件中出现的次数。

我尝试专门为循环创建一个新的文件流，因为它已在前一部分代码中使用。我还尝试将 long long int 转换为数组和 print 语句，但这只会给我更大的数字。

  FILE* input;
  FILE* output;
  input  = fopen("input.txt", "r");
  output = fopen("report.txt", "w");
  ...

  char letterTemp;
  float letterMax;
  int upperCounter = 0;
  int lowerCounter = 0;
  char alphaChars[26];
  int charCounter[26];

  for (char c = 'a'; c <= 'z'; ++c) {
    alphaChars[c - 'a'] = c; 
  }

  for (int i = 0; i < 26; i++) {
    fopen("input.txt", "r");

    while ((letterTemp = fgetc(input)) != EOF) {
      if (alphaChars[i] == letterTemp) {
        lowerCounter++;
        charCounter[i]++;
      }
      else if (toupper(alphaChars[i]) == letterTemp) {
        upperCounter++;
        charCounter[i]++;
      }
    }
    fclose(input);
  }
  letterMax = lowerCounter + upperCounter;

  fprintf(output, "LETTER STATISTICS\n\nCategory                How many in file    %% of all letters\n----------------------------------------------------------------------\nUppercase%31d%20.2f %%\nLowercase%31d%20.2f %%\n", upperCounter, 100 * upperCounter / letterMax, lowerCounter, 100 * lowerCounter / letterMax);

  for (int i = 0; i < 25; i++) {
    fprintf(output, "%c%39d%20.2f %%\n", alphaChars[i], charCounter[i], 100 * charCounter[i] / letterMax);
  }

这会给我...

LETTER STATISTICS

Category                How many in file    % of all letters
----------------------------------------------------------------------
Uppercase                              9               12.16 %
Lowercase                             65               87.84 %
a                             2080375142         25393028.00 %
b                                  32766            44278.38 %
c                             2080375153         25393042.00 %
d                                  32767            44279.73 %
e                             -677299551         13371914.00 %
f                                  32734            44235.14 %
g                                      0                0.00 %
h                                      2                2.70 %
i                                      7                9.46 %
j                                      0                0.00 %
k                                      0                0.00 %
l                                      7                9.46 %
m                                      2                2.70 %
n                                      1                1.35 %
o                                      7                9.46 %
p                                      1                1.35 %
q                             2081514112         26932176.00 %
r                                  32770            44283.79 %
s                             -677300459         13370687.00 %
t                                  32735            44236.49 %
u                                      2                2.70 %
v                                      1                1.35 %
w                                      2                2.70 %
x                                      1                1.35 %
y                                      5                6.76 %

这里发生了什么？

Answer 1

由于原帖使用了toupper，因此使用tolower、islower和isupper来避免多次读取文件并循环匹配字符。

#include <stdio.h>
#include <ctype.h>

int main ( ) {
    FILE* input = NULL;
    FILE* output = NULL;
    int letterTemp;
    float letterMax;
    int upperCounter = 0;
    int lowerCounter = 0;
    int charCounter[256] = { 0};//256 for all 8 bit values

    if ( NULL != ( input = fopen ( "input.txt", "r"))) {

        while ( ( letterTemp = fgetc ( input)) != EOF) {
            if ( islower ( letterTemp)) {//lower case
                lowerCounter++;
                charCounter[letterTemp]++;//increment count
            }
            if ( isupper ( letterTemp)) {//upper case
                upperCounter++;
                charCounter[tolower ( letterTemp)]++;//increment lower case count
            }
        }
        fclose ( input);
        letterMax = lowerCounter + upperCounter;

        if ( NULL != ( output = fopen ( "report.txt", "w"))) {
            fprintf ( output , "LETTER STATISTICS\n\n");
            fprintf ( output , "Category                How many in file    %% of all letters\n");
            fprintf ( output , "--------------------------------------------------------------\n");
            fprintf ( output , "Uppercase%31d%20.2f %%\nLowercase%31d%20.2f %%\n"
            , upperCounter
            , 100 * upperCounter / letterMax
            , lowerCounter
            , 100 * lowerCounter / letterMax);

            for (int i = 0; i < 256; i++) {
                if ( islower( i)) {//only print lower case values
                    fprintf ( output, "%c%39d%20.2f %%\n"
                    , i
                    , charCounter[i]
                    , 100 * charCounter[i] / letterMax);
                }
            }
            fclose ( output);
        }
        else {
            fprintf ( stderr, "could not open output file\n");
        }
    }
    else {
        fprintf ( stderr, "could not open input file\n");
    }
    return 0;
}