1. When watching the video, there is such a point of view, the video connection: The video connection of station B is at 35 minutes . That is, when defining the array, you cannot use variables. The code is as follows. The video says that VS2012 compilation will report an error, but I use Dev-c++ There was no error when compiling, and the compiling and running passed. For this problem, I haven't figured it out yet?
#include <stdio.h>
int main()
{
int num=4;
int a[num]={
1,2,3,4};
return 0;
}
2. It strlenis used to calculate the length of the string,
but sometimes the compiler will report an error 'strlen' was not declared in this scope, as shown below:
At this time, you only need to add the header file #include <string.h>to solve the problem.
#include <stdio.h>
#include <string.h>
int main()
{
char a1[]={
"abc"};//数组
//"abc"---'a''b''c''\0'--'\0'字符串的结束标志
char a2[]={
'a','b','c','\0'};
char a3[]={
'a','b','c'};
printf("%d\n",strlen(a1));//strlen--计算字符串长度的
printf("%d\n",strlen(a2));
printf("%d\n",strlen(a3));
return 0;
}
3.报错C [Warning] deprecated conversion from string constant to ‘char*’
#include "stdio.h"
char *str1 = "Hello";
char str2[] = "Hello";
int main()
{
printf("%d %d", sizeof(str1), sizeof(str2));
}
The solution is as follows: add a const
#include "stdio.h"
const char *str1 = "Hello";
char str2[] = "Hello";
int main()
{
printf("%d %d", sizeof(str1), sizeof(str2));
}