lvalue required as left operand of assignment

Question

Why am I getting   lvalue required as left operand of assignment   with a single string comparison  How can I fix this in C   if  strcmp  hello    hello     0    Thanks

User · Answer

You cannot assign an rvalue to an rvalue.

if (strcmp("hello", "hello") = 0)

is wrong. Suggestions:

if (strcmp("hello", "hello") == 0)
                              ^

= is the assign operator.
== is the equal to operator.
I know many new programmers are confused with this fact.

User · Answer

You need to compare  not assign   if  strcmp  hello    hello      0                                   Because you want to check if the result of strcmp  hello    hello   equals to 0   About the error      lvalue required as left operand of   assignment   lvalue means an assignable value  variable   and in assignment the left value to the   has to be lvalue  pretty clear    Both function results and constants are not assignable  rvalues   so they are rvalues  so the order doesn t matter and if you forget to use    you will get this error   edit  I consider it a good practice in comparison to put the constant in the left side  so if you write   instead of     you will get a compilation error  for example   int a   5  if  a   0     Always evaluated as false  no error                  vs   int a   5  if  0   a     Generates compilation error  you cannot assign a to 0  rvalue                   see first answer to this question  https   stackoverflow com questions 2349378 new-programming-jargon-you-coined

User · Answer

You are trying to assign a value to a function  which is not possible in C  Try the comparison operator instead   if  strcmp  hello    hello      0

User · Answer

if  strcmp  hello    hello     0    Is trying to assign 0 to function return value which isn t lvalue   Function return values are not lvalue  no storage for it   so any attempt to assign value to something that is not lvalue result in error   Best practice to avoid such mistakes in if conditions is to use constant value on left side of comparison  so even if you use     instead       constant being not lvalue will immediately give error and avoid accidental value assignment and causing false positive if condition

User · Answer

Change   to    i e if  strcmp  hello    hello      0   You want to compare the result of strcmp   to 0  So you need     Assigning it to 0 won t work because rvalues cannot be assigned to

User · Answer

I found that an answer to this issue when dealing with math is that the operator on the left hand side must be the variable you are trying to change  The logic cannot come first   coin1   coin2   coin3   coinTotal     Wrong  coinTotal   coin1   coin2   coin3     Right   This isn t a direct answer to your question but it might be helpful to future people who google the same thing I googled

[c] lvalue required as left operand of assignment

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