C Language Interview Questions & Answers
C Language Interview Online Test
1. How do you decide which integer type to use?
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2. What should the 64-bit type on new, 64-bit machines be?
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3. What's the best way to declare and define global variables?
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4. What does extern mean in a function declaration?
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5. What's the auto keyword good for?
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6. I can't seem to define a linked list node which contains a pointer to itself.
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7. How do I declare an array of N pointers to functions returning pointers to functions returning pointers to characters?
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8. How can I declare a function that returns a pointer to a function of its own type?
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9. My compiler is complaining about an invalid redeclaration of a function, but I only define it once.
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10. What can I safely assume about the initial values of variables which are not explicitly initialized?
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11. Why can't I initialize a local array with a string?
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12. What's wrong with "char *p = malloc(10);" ?
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13. What is the difference between char a[] = "string"; and char *p = "string"; ?
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14. How do I initialize a pointer to a function?
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15. What's the difference between struct x1 { ... }; and typedef struct { ... } x2; ?
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16. What's the best way of implementing opaque (abstract) data types in C?
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17. I came across some code that declared a structure with the last member an array of one element, and then did some tricky allocation to make it act like the array had several elements.Is this legal or portable?
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18. Why can't you compare structures?
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19. How are structure passing and returning implemented?
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20. Can I pass constant values to functions which accept structure arguments?
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21. How can I read/write structures from/to data files?
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22. How can I turn off structure padding?
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23. Why does sizeof report a larger size than I expect for a structure type?
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24. How can I determine the byte offset of a field within a structure?
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25. How can I access structure fields by name at run time?
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26. I have a program which works correctly, but dumps core after it finishes. Why?
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27. Can I initialize unions?
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28. What is the difference between an enumeration and a set of preprocessor #defines?
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29. Is there an easy way to print enumeration values symbolically?
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30. Why doesn't the code "a[i] = i++;" work?
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31. Under my compiler, the code "int i = 7;printf("%d\n", i++ * i++);" prints 49. Regardless of the order
of evaluation, shouldn't it print 56?
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32. How could the code "int i = 3; i = i++;" ever give 7?
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33. Don't precedence and parentheses dictate order of evaluation?
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34. But what about the && and || operators?
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35. What's a "sequence point"?
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36. So given a[i] = i++; we don't know which cell of a[] gets written to, but i does get incremented by one, right?
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37. If I'm not using the value of the expression, should I use i++ or ++i to increment a variable?
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38. Why doesn't the code "int a = 1000, b = 1000; long int c = a * b;" work?
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39. Can I use ?: on the left-hand side of an assignment expression?
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40. What's wrong with "char *p; *p = malloc(10);"?
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41. Does *p++ increment p, or what it points to?
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42. I have a function which accepts, and is supposed to initialize,a pointer, but the pointer in the caller remains unchanged.
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43. I have a function which accepts a pointer to an int. How can I pass a constant like 5 to it?
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44. Does C even have "pass by reference"?
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45. I've seen different methods used for calling functions via pointers
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46. What is this infamous null pointer, anyway?
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47. How do I get a null pointer in my programs?
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48. Is the abbreviated pointer comparison "if(p)" to test for non-null pointers valid?
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49. What is NULL and how is it #defined?
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50. How should NULL be defined on a machine which uses a nonzero bit pattern as the internal representation of a null pointer?
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51. What does static variable mean?
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52. What is a pointer?
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53. What is a structure?
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54. What is a union?
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55. What are the differences between structures and union?
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56. What are the differences between structures and arrays?
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57. In header files whether functions are declared or defined?
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58. What are the differences between malloc () and calloc ()?
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59. What are macros? What are its advantages and disadvantages?
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60. Difference between pass by reference and pass by value?
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61. What is static identifier?
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62. Where is the auto variables stored?
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63. Where does global, static, and local, register variables, free memory and C Program instructions get stored?
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64. Difference between arrays and linked list?
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65. What are enumerations?
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66. What are register variables? What are the advantages of using register variables?
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67. What is the use of typedef?
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68. Can we specify variable field width in a scanf() format string? If possible how?
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69. Out of fgets() and gets() which function is safe to use and why?
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70. Difference between strdup and strcpy?
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71. What is recursion?
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72. Differentiate between for loop and a while loop? What are it uses?
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73. What is storage class? What are the different storage classes in C?
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74. What the advantages of using Unions?
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75. What is the difference between Strings and Arrays?
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76. What is a far pointer? Where we use it?
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77. What is a huge pointer?
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78. What is a normalized pointer, how do we normalize a pointer?
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79. What is near pointer?
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80. In C, why is the void pointer useful? When would you use it?
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81. What is a NULL Pointer? Whether it is same as an uninitialized pointer?
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82. Are pointers integer?
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83. What does the error ‘Null Pointer Assignment means and what causes this error?
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84. What is generic pointer in C?
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85. Are the expressions arr and &arr same for an array of integers?
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86. IMP>How pointer variables are initialized?
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87. What is static memory allocation?
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88. What is dynamic memory allocation?
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89. What is the purpose of realloc?
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90. What is an array of pointers?
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91. Difference between linker and linkage?
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92. Is it possible to have negative index in an array?
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93. Why is it necessary to give the size of an array in an array declaration?
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94. What modular programming?
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95. What is a function?
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96. What is an argument?
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97. What are built in functions?
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98. Difference between formal argument and actual argument?
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99. Is it possible to have more than one main() function in a C program ?
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100. What is the difference between an enumeration and a set of pre-processor # defines?
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101. How are Structure passing and returning implemented by the complier?
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102. what is the similarity between a Structure, Union and enumeration?
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103. Can a Structure contain a Pointer to itself?
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104. How can we read/write Structures from/to data files?
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105. Write a program which employs Recursion?
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106. Write a program which uses Command Line Arguments?
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107. What do the ‘c and ‘v in argc and argv stand for?
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108. what are C tokens?
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109. What are C identifiers?
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110. What is preincrement and post increment?
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111. What is the maximum combined length of command line arguments including the space between adjacent arguments?
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112. What is the difference between the functions memmove() and memcpy()?
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113. What is a file?
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114. what are the types of file?
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115. what is a stream?
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116. What is meant by file opening?
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117. What is FILE?
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118. What is a file pointer?
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119. How is a file closed ?
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120. Are the expressions *ptr ++ and ++ *ptr same?
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121. What would be the equivalent pointer expression foe referring the same element as
a[p][q][r][s] ?
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122. Are the variables argc and argv are always local to main?
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123. Can main () be called recursively?
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124. IMP>Can we initialize unions?
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125. whats the difference between these two declarations?
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126. Why doesnt this code: a[i] = i++; work?
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127. WHy doesnt struct x { … };
x thestruct;
work?
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128. Why cant we compare structures?
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129. Can we use any name in place of argv and argc as command line arguments ?
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130. What is the difference between an Interface and an Abstract class?
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