The CLC (compare logical characters) instruction compares the first and second operands and sets the condition code to reflect the result of the comparison. The comparison is a logical comparison (not a numeric comparison), so it is used for character data. The two operands are compared bit by bit until a difference is found or until all bits are compared and the operands are found to be equal. The condition code is set as follows:

Relation of Operands | Result of Comparison | Value of Condition Code |
---|---|---|

operand1 == operand2 | equal | 00 |

operand1 < operand2 | low | 01 |

operand1 > operand2 | high | 10 |

Given the following definitions:

ONE DC C'ABCDE' TWO DC C'12345' THREE DC C'ABX1239' FOUR DC C'ABC' FIVE DC C'123' SIX DC C' ABCD' SEVEN DC C'BBC'

The DC statements shown above result in the following data (shown in character and hex) in storage:

A B C D E 1 2 3 4 5 A B X 1 2 3 9 A B C 1 2 3 A B C D B B C C1C2C3C4C5F1F2F3F4F5C1C2E7F1F2F3F9C1C2C3F1F2F340C1C2C3C4C2C2C3 ONE TWO THREE FOUR FIVE SIX SEVEN

The following table shows the results of CLC instructions. Each instruction starts with the initial data given above.

CLC Instruction | Operand 1 | Operand 2 | Result | Condition Code |
---|---|---|---|---|

Implicit Comparisons | ||||

CLC ONE,TWO | C1C2C3C4C5 | F1F2F3F4F5 | low | 01 |

CLC ONE,FOUR | C1C2C3C4C5 | C1C2C3F1F2 | low | 01 |

CLC FOUR,ONE | C1C2C3 | C1C2C3 | equal | 00 |

CLC SEVEN,FOUR | C2C2C3 | C1C2C3 | high | 10 |

CLC FOUR,SIX+1 | C1C2C3 | C1C2C3 | equal | 00 |

CLC ONE,SIX | C1C2C3C4C5 | 40C1C2C3C4 | high | 10 |

CLC THREE,ONE | C1C2E7F1F2F3F9 | C1C2C3C4C5F1F2 | high | 10 |

Explicit Comparisons | ||||

CLC TWO(3),FIVE | F1F2F3 | F1F2F3 | equal | 00 |

CLC THREE+3(3),FIVE | F1F2F3 | F1F2F3 | equal | 00 |

CLC FIVE(8),TWO | F1F2F340C1C2C3C4 | F1F2F3F4F5C1C2E7 | low | 01 |

CLC SIX+2(1),SEVEN+1 | C2 | C2 | equal | 00 |

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