Difference between JE/JNE and JZ/JNZ

JE and JZ are just different names for exactly the same thing: a conditional jump when ZF (the “zero” flag) is equal to 1.

(Similarly, JNE and JNZ are just different names for a conditional jump when ZF is equal to 0.)

You could use them interchangeably, but you should use them depending on what you are doing:

  • JZ/JNZ are more appropriate when you are explicitly testing for something being equal to zero:dec ecx jz counter_is_now_zero
  • JE and JNE are more appropriate after a CMP instruction:cmp edx, 42 je the_answer_is_42 (A CMP instruction performs a subtraction, and throws the value of the result away, while keeping the flags; which is why you get ZF=1 when the operands are equal and ZF=0 when they’re not.)

Related Posts:

  1. What’s the purpose of the LEA instruction?
  2. Understanding cmp instruction
  3. What does the MOVZBL instruction do in IA-32 AT&T syntax?
  4. What’s the purpose of the LEA instruction?
  5. How to move ST(0) to EAX?
  6. The point of test %eax %eax
  7. Assembly: How does fld st(0) duplicates the top stack value in the following code?
  8. What does the MOVZBL instruction do in IA-32 AT&T syntax?
  9. What’s the purpose of the LEA instruction?
  10. The difference between cmpl and cmp
  11. x86 cmpl and jne
  12. What is the function of the push / pop instructions used on registers in x86 assembly?
  13. What is callq instruction?
  14. Purpose of ESI & EDI registers?
  15. What are the ESP and the EBP registers?
  16. IDIV operation in assembly (understanding)
  17. explanation about push ebp and pop ebp instruction in assembly
  18. x86 assembly: How does the ‘subl’ command work in AT&T syntax
  19. what does the cmpq instruction do?
  20. Purpose of ESI & EDI registers?
  21. Bubble sort on array on Assembly Language
  22. Nasm Error: invalid combination of opcode and operands
  23. When and why do we sign extend and use cdq with mul/div?
  24. How do AX, AH, AL map onto EAX?
  25. pop or add esp, 4 ? What is the difference?
  26. What is the difference between MOV and LEA?
  27. `testl` eax against eax?
  28. Printing out a number in assembly language?
  29. What does `dword ptr` mean?
  30. Difference between JA and JG in assembly
  31. what does the the dword operand do in assembly
  32. What does the LEAL assembly instruction do?
  33. [Binary Bomb – Phase 4
  34. assembly “mov” instruction
  35. Why shift a bit using sll and such in MIPs Assembly?
  36. Assembly code vs Machine code vs Object code?
  37. Understanding how `lw` and `sw` actually work in a MIPS program
  38. need help understanding the movzbl call in this function
  39. MIPS: lw (load word) instruction
  40. What is the meaning of XOR in x86 assembly?
  41. What does the BEQ instruction do exactly?
  42. What’s the size of a QWORD on a 64-bit machine?
  43. MIPS assembly for a simple for loop
  44. Difference between JA and JG in assembly
  45. mips .word function and differences between 2 codes
  46. Display value found at given address gdb
  47. Why doesn’t there exists a subi opcode for MIPS?
  48. Convert C program into assembly code
  49. LC3 LEA instruction and the value stored
  50. What exactly does the lb instruction do?
  51. lc3 LDR instruction and the value stored
  52. What is the difference between la and li in opcodes in MIPS?
  53. What does movslq do?
  54. Assembly language je jump function
  55. What are .S files?
  56. Why are rbp and rsp called general purpose registers?
  57. x86 Assembly pointers
  58. what is the use of ori in this part of MIPS code?
  59. Storing a user’s input in MIPS
  60. Integer absolute value in MIPS?
  61. xorl %eax – Instruction set architecture in IA-32
  62. MIPS Assembly – lui $t0, 4097?
  63. Greater than, less than equal, greater than equal in MIPS
  64. Assembly addq clarification
  65. Which variable size to use (db, dw, dd) with x86 assembly?
  66. MIPS program jr $ra instructions and stack handling
  67. Assembly – JG/JNLE/JL/JNGE after CMP
  68. Subtract two input numbers
  69. writing functions in assembler
  70. JNZ & CMP Assembly Instructions
  71. X86 assembly – Handling the IDIV instruction
  72. Assembly language (MIPS) difference betweent addi and add
  73. MIPS Address out of range (MARS)
  74. Difference between “addi” and “add” for pseudoinstruction “move” in MIPS?
  75. sorting array in mips (assembly)
  76. what is a file handle and where it is useful for a programmer?
  77. How does `Skipcond` work in the MARIE assembly language?
  78. What are callee and caller saved registers?
  79. Multiplication by a power of 2 using Logical shifts in MIPS assembly
  80. MIPS instruction and machine code
  81. Convert from Java to MIPS
  82. Understanding Assembly MIPS .ALIGN and Memory Addressing
  83. error A2022: instruction operands must be the same size
  84. What’s the difference between a word and byte?
  85. Assembly Language – How to do Modulo?
  86. Difference between movq and movabsq in x86-64
  87. What is the jmpq command doing in this example
  88. Assembly – JZ instruction after CMP
  89. What does bx lr do in ARM assembly language?
  90. `js` and `jb` instructions in assembly
  91. How does the ARM architecture differ from x86? [closed]
  92. Is it possible to “decompile” a Windows .exe? Or at least view the Assembly?
  93. Why is Windows 32-bit called Windows x86 and not Windows x32?
  94. ARM Assembler – How do I use CMP, BLT and BGT?
  95. C to assembly – leaq instruction
  96. what does .space do in mips?
  97. Understanding %rip register in intel assembly
  98. How can one see content of stack with GDB?
  99. What is the difference between Trap and Interrupt?
  100. MIPS to C Translation

Leave a Comment

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)