When and why to use malloc?

malloc is used for dynamic memory allocation. As said, it is dynamic allocation which means you allocate the memory at run time. For example when you don’t know the amount of memory during compile time.

One example should clear this. Say you know there will be maximum 20 students. So you can create an array with static 20 elements. Your array will be able to hold maximum 20 students. But what if you don’t know the number of students? Say the first input is the number of students. It could be 10, 20, 50 or whatever else. Now you will take input n = the number of students at run time and allocate that much memory dynamically using malloc.

This is just one example. There are many situations like this where dynamic allocation is needed.

Have a look at the man page malloc(3).

Related Posts:

  1. Difference between malloc and calloc?
  2. Process finished with exit code 11 | Error during malloc [duplicate]
  3. Using Dynamic Memory allocation for arrays
  4. Incompatible implicit declaration of built-in function ‘malloc’
  5. Need more information about Aborted (core dumped)
  6. What is the cause of flexible array member not at end of struct error?
  7. Memory Clobbering Error
  8. Uninitialized value was created by a heap allocation
  9. Allocating string with malloc
  10. Allocating char array using malloc
  11. How to use execvp()
  12. How to use execvp() to execute a command
  13. How does strtok() split the string into tokens in C?
  14. What is *(uint32_t*)?
  15. what is Segmentation fault (core dumped)? [duplicate]
  16. uint8_t vs unsigned char
  17. What is the difference between ++i and i++?
  18. Using boolean values in C
  19. What does “collect2: error: ld returned 1 exit status” mean?
  20. How to convert an int to string in C?
  21. typedef struct vs struct definitions [duplicate]
  22. How to print in C
  23. What can be the reasons of connection refused errors?
  24. What is newline character — ‘\n’
  25. Why does ENOENT mean “No such file or directory”?
  26. What does the question mark character (‘?’) mean?
  27. Cannot figure out how to use getchar(); in C
  28. makefile:4: *** missing separator. Stop
  29. c stack smashing detected
  30. Undefined reference to pthread_create
  31. Convert char to int in C and C++
  32. What is Bit Masking?
  33. Strings and character with printf
  34. What are .a and .so files?
  35. So what does “return 0” actually mean?
  36. Why is the gets function so dangerous that it should not be used?
  37. What does “collect2: error: ld returned 1 exit status” mean?
  38. Warning comparison between pointer and integer
  39. Using ssize_t vs int
  40. Why a warning of “control reaches end of non-void function” for the main function?
  41. How do I use extern to share variables between source files?
  42. Cannot assign requested address – possible causes?
  43. error: called object is not a function or function pointer
  44. munmap_chunk(): invalid pointer
  45. C read file line by line
  46. warning: incompatible implicit declaration of built-in function ‘xyz’
  47. No Symbol Table using GDB on Compiled Programs
  48. What is char ** in C?
  49. What is a bus error? Is it different from a segmentation fault?
  50. Get the current time in C
  51. where does stdio.o live in linux machine?
  52. Get text from user input using C
  53. How to trigger SIGUSR1 and SIGUSR2?
  54. How do I lowercase a string in C?
  55. warning: expression result unused
  56. conflicting types error when compiling c program using gcc
  57. Get the current time in C
  58. error: indirection requires pointer operand (‘int’ invalid)
  59. What is a file with extension .a?
  60. What is the difference between exit(0) and exit(1) in C?
  61. error: indirection requires pointer operand (‘int’ invalid)
  62. Finding the length of a Character Array in C
  63. Return char[]/string from a function
  64. Valgrind: Invalid read of size 1
  65. How to print a char array in C through printf?
  66. How to clear all the elements of array in C?
  67. Constant pointer vs Pointer to constant
  68. Variable warning set but not used
  69. Expected declaration specifier error in function
  70. Why I do get “Cannot find bound of current function” when I overwrite the ret address of a vulnerable program?
  71. How do malloc() and free() work?
  72. strcmp not working
  73. C char* to int conversion
  74. error: aggregate value used where an integer was expected
  75. char pointers: invalid conversion from ‘char*’ to ‘char’?
  76. Incorrect checksum for freed object on malloc
  77. Does C have a string type?
  78. What are .axf files?
  79. printf format specifiers for uint32_t and size_t
  80. error: function returns address of local variable
  81. What is an simple example of copy_from_user
  82. What is `S_ISREG()`, and what does it do?
  83. typedef struct pointer definition
  84. Math constant PI value in C
  85. Return a `struct` from a function in C
  86. Reaching EOF with fgets
  87. C: scanf to array
  88. The code does not execute properly. Try to figure out why
  89. What are “prototypes” in a C program?
  90. ld.exe: cannot open output file … : Permission denied
  91. How to read from input until newline is found using scanf()?
  92. What’s the difference between “mod” and “remainder”?
  93. What is char ** in C? [duplicate]
  94. undefined reference to `std::ios_base::Init::Init()’
  95. previous declaration of ‘function’ was here in C [duplicate]
  96. segmentation fault using scanf
  97. realloc(): invalid next size when reallocating to make space for strcat on char *
  98. How to Compare 2 Character Arrays [duplicate]
  99. Error: Conversion to non-scalar type requested
  100. segmentation fault with strcpy [duplicate]

Leave a Comment