Error:incompatible types in assignment of 'const char[5]' to 'char[10]'

问题:

I have defined c as

char c[][10] 

in function definition and used it like c[i]="gray";

Whats wrong? I searched on net, it shows the same syntax.

Thanks.

回答1:

You cannot use assignment (=) on an array. If you change c to an array of pointers, that might work, depending on what you need to do with it.

const char *c[20]; c[i] = "gray"; 

Or if the declared type must be array of arrays, you could use strncpy:

char c[20][10]; strncpy(c[i], "gray", sizeof(c[i])); 

回答2:

The problem is that arrays are not assignable in C. String constants like "gray" are character array constants: in this case, the type is char[5] (4 + 1 for the terminating null).

If you know that the destination array is large enough to hold the desired string, you can use strcpy to copy the string like so:

// Make sure you know that c[i] is big enough! strcpy(c[i], "gray"); 

A better idea is to use a safer function such as strlcpy (BSD-based systems and Mac OS X) or strcpy_s (Windows):

strlcpy(c[i], "gray", 10);  // 10 is the size of c[i] 

However, these functions are platform-specific and not all that portable. You could also roll your own implementation if speed is not an issue:

size_t strlcpy(char *dst, const char *src, size_t size) {     size_t len = 0;     while(size > 1 && *src)     {         *dst++ = *src++;         size--;         len++;     }     if(size > 0)         *dst = 0;     return len + strlen(src);     } 

Do not use strncpy, since it could potentially leave you with a non-null-terminated string

回答3:

Try using strcpy() (found in the cstring header) instead of just plain assignment.

回答4:

this code will work and make the correct assignements in 3 different ways:

#include <iostream> #include <cstring>  using namespace std;  int main() {     string myString = "hello my friends from Brazil";     char charOut[myString.size()];     strncpy(charOut, myString.c_str(), myString.size());     std::cout << "Char by strncpy string var  " << charOut << std::endl;      const char *charOut2;     charOut2 = "sup my homies in L.A.";     std::cout << "Char by const  " << charOut2 << std::endl;      string myString2 = "hallo mein bruder in Berlin";     char charOut3[myString2.size()];     strcpy(charOut3, myString2.c_str());     std::cout << "Char by strcpy string var  " << charOut3 << std::endl; } 

runs ok on ubuntu servers. did not test on other systems.

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