execute if score @s a = @e[limit=1,name=b] a run say 相等

如果是1.12.X呢？

scoreboard players operation @s a -= @e[c=1,name=b] a
execute @s[score_a_min=0,score_a=0] ~ ~ ~ say 相等


不过这样会改玩家本身 a 的分数。如果不想改，可以再建一个新的记分板 c，然后
scoreboard players operation @s c = @s a
scoreboard players operation @s c -= @e[c=1,name=b] a
execute @s[score_c_min=0,score_c=0] ~ ~ ~ say 相等

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