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  1. #include <iostream>
  2. #include <sstream>
  3. #include <string>
  4. #include <iomanip>
  5.  
  6. using std::cin;
  7. using std::cout;
  8. using std::endl;
  9.  
  10. void parse_as_char(std::istream& is)
  11. {
  12. 	char c1 = '#', c2 = '#', c3 = '#';
  13.  
  14. 	is.clear();
  15. 	is >> c1;
  16. 	cout << "(1) c1='" << c1 << "', is.good()=" << is.good() << ", is.eof()=" << is.eof() << endl;
  17. 	is >> c2;
  18. 	cout << "(2) c2='" << c2 << "', is.good()=" << is.good() << ", is.eof()=" << is.eof() << endl;
  19. 	is >> c3;
  20. 	cout << "(3) c3='" << c3 << "', is.good()=" << is.good() << ", is.eof()=" << is.eof() << endl;
  21. }
  22.  
  23. void parse_as_str(std::istream& is)
  24. {
  25. 	std::string s1 = "#", s2 = "#", s3 = "#";
  26.  
  27. 	is.clear();
  28. 	is >> s1;
  29. 	cout << "(1) s1=\"" << s1 << "\", is.good()=" << is.good() << ", is.eof()=" << is.eof() << endl;
  30. 	is >> s2;
  31. 	cout << "(2) s2=\"" << s2 << "\", is.good()=" << is.good() << ", is.eof()=" << is.eof() << endl;
  32. 	is >> s3;
  33. 	cout << "(3) s3=\"" << s3 << "\", is.good()=" << is.good() << ", is.eof()=" << is.eof() << endl;
  34. }
  35.  
  36. void test_parse_as_str(const char* szInput)
  37. {
  38. 	std::istringstream ist;
  39.  
  40. 	cout << __FUNCTION__ << ": Input=\"" << szInput << "\"" << endl;
  41. 	ist.str(szInput);
  42. 	parse_as_str(ist);
  43. 	cout << endl;
  44. }
  45.  
  46. void test_parse_as_char(const char* szInput)
  47. {
  48. 	std::istringstream ist;
  49.  
  50. 	cout << __FUNCTION__ << ": Input=\"" << szInput << "\"" << endl;
  51. 	ist.str(szInput);
  52. 	parse_as_char(ist);
  53. 	cout << endl;
  54. }
  55.  
  56. bool parse_as_string_with_common_logic(std::istream& is, std::string& s, bool& bErr)
  57. {
  58. 	char c;
  59. 	is >> c;
  60. 	if (!is.good()) {
  61. 		if (is.eof()) {
  62. 			/*pass*/
  63. 		}
  64. 		else {
  65. 			bErr = true;
  66. 		}
  67. 		return false;
  68. 	}
  69. 	is.unget();
  70. 	is >> s;
  71. 	return true;		// 固定値trueを返すと最後のsが呼び出し元に正しく認識される。
  72. 						// 最後のsを読み取り、入力に引き続く空白文字が無い場合は
  73. 						// ここに来たとき!is.good()が成立しているため、is.good()を返すロジックはNG。
  74. }
  75.  
  76. void test_parse_as_string_with_common_logic(const char* szInput, bool& bErr)
  77. {
  78. 	std::string str;
  79.  
  80. 	cout << __FUNCTION__ << ": Input=\"" << szInput << "\"" << endl;
  81. 	std::istringstream ist;
  82. 	ist.str(szInput);
  83.  
  84. 	size_t i = (size_t)0;
  85. 	while (parse_as_string_with_common_logic(ist, str, bErr)) {
  86. 		i++;
  87. 		cout << "(" << i << ") str=\"" << str << "\", bErr=" << bErr << endl;
  88. 	}
  89. 	cout << "(" << "F" << ") str=\"" << str << "\", bErr=" << bErr << endl;
  90.  
  91. 	cout << endl;
  92. }
  93.  
  94. int main()
  95. {
  96. 	bool bErr = false;
  97.  
  98. 	// ケースA)
  99. 	cout << "Case A)" << endl;
  100. 	test_parse_as_char("A B");		// Bの後ろに空白無し --> 'B' を読んだ後の is >> c3 で初めて!is.good()かつis.eof()成立(getc()と同じ挙動)
  101.  
  102. 	// ケースA')
  103. 	cout << "Case A')" << endl;
  104. 	test_parse_as_char("A B ");		// Bの後ろに空白有り --> (同上)
  105.  
  106. 	// ケースB)
  107. 	cout << "Case B)" << endl;
  108. 	test_parse_as_str("A B");		// Bの後ろに空白無し --> "B" を読んだ時点で!is.good()かつis.eof()成立
  109.  
  110. 	// ケースC)
  111. 	cout << "Case C)" << endl;
  112. 	test_parse_as_str("A B ");		// Bの後ろに空白有り --> "B" を読んだ後の is >> s3 で初めて!is.good()かつis.eof()成立(getc()と同じ挙動)
  113.  
  114. 	// 共通判定ロジックによるCase Bの読み取り
  115. 	cout << "Case B with common logic:" << endl;
  116. 	test_parse_as_string_with_common_logic("A B", bErr);
  117.  
  118. 	// 共通判定ロジックによるCase Cの読み取り
  119. 	cout << "Case C with common logic:" << endl;
  120. 	test_parse_as_string_with_common_logic("A B ", bErr);
  121. }
  122.  
Success #stdin #stdout 0.01s 5320KB
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Standard input is empty
stdout
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Case A)
test_parse_as_char: Input="A B"
(1) c1='A', is.good()=1, is.eof()=0
(2) c2='B', is.good()=1, is.eof()=0
(3) c3='#', is.good()=0, is.eof()=1

Case A')
test_parse_as_char: Input="A B "
(1) c1='A', is.good()=1, is.eof()=0
(2) c2='B', is.good()=1, is.eof()=0
(3) c3='#', is.good()=0, is.eof()=1

Case B)
test_parse_as_str: Input="A B"
(1) s1="A", is.good()=1, is.eof()=0
(2) s2="B", is.good()=0, is.eof()=1
(3) s3="#", is.good()=0, is.eof()=1

Case C)
test_parse_as_str: Input="A B "
(1) s1="A", is.good()=1, is.eof()=0
(2) s2="B", is.good()=1, is.eof()=0
(3) s3="#", is.good()=0, is.eof()=1

Case B with common logic:
test_parse_as_string_with_common_logic: Input="A B"
(1) str="A", bErr=0
(2) str="B", bErr=0
(F) str="B", bErr=0

Case C with common logic:
test_parse_as_string_with_common_logic: Input="A B "
(1) str="A", bErr=0
(2) str="B", bErr=0
(F) str="B", bErr=0
https://ideone.com/eaYGEt
language:
C++14 (gcc 8.3)
created:
79 days ago
visibility:
secret

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