📌 Author: Foxny
📃 Update record: July 8, 2021
❌ Corrigendum record: None
📜 This article states: due to the limited level of the author, it is inevitable that there are errors and inaccuracies in this article. I also want to know these errors. I sincerely hope the readers can criticize and correct them!
📝 Example:
🔍 Topic explanation display:
Array written test questions (answer + detailed explanation)
8 big questions (63 small questions in total), 1 point for each small question, the full score is 63 points
📚 explain:
① It is suggested to take out paper and pen to write the results you think;
② It is suggested not to look at the answers first, and then look at the answers for verification after writing;
③ There are hyperlinks in front of some topics corresponding to knowledge points, you can choose to review by yourself;
④ For the wrong question, you can see the analysis part below the answer to the question for in-depth understanding;
⑤ You can reply to several questions you have done correctly in the comment area;
First question:
1 point for each sub question, full score 7 points
📌 review: [vitamin C language] Chapter 5 - operators (0x05 type length of operand sizeof)
💬 Predict the running result of the following code (sizeof)
int main()
{
int a[] = {1, 2, 3, 4}; // One dimensional array
/* 1 */ printf("%d\n", sizeof(a));
/* 2 */ printf("%d\n", sizeof(a + 0));
/* 3 */ printf("%d\n", sizeof(*a));
/* 4 */ printf("%d\n", sizeof(a + 1));
/* 5 */ printf("%d\n", sizeof(a[1]));
/* 6 */ printf("%d\n", sizeof(&a));
/* 7 */ printf("%d\n", sizeof(*&a));
/* 8 */ printf("%d\n", sizeof(&a + 1));
/* 9 */ printf("%d\n", sizeof(&a[0]));
/* 10 */ printf("%d\n", sizeof(&a[0] + 1));
return 0;
}💡 answer:
/* 1 */ printf("%d\n", sizeof(a)); // 16
/* 2 */ printf("%d\n", sizeof(a + 0)); // 4/8
/* 3 */ printf("%d\n", sizeof(*a)); // 4
/* 4 */ printf("%d\n", sizeof(a + 1)); // 4/8
/* 5 */ printf("%d\n", sizeof(a[1])); // 4
/* 6 */ printf("%d\n", sizeof(&a)); // 4/8
/* 7 */ printf("%d\n", sizeof(*&a)); // 16
/* 8 */ printf("%d\n", sizeof(&a + 1)); // 4/8
/* 9 */ printf("%d\n", sizeof(&a[0])); // 4/8
/* 10 */ printf("%d\n", sizeof(&a[0] + 1)); // 4/8🔑 Resolution:
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Second question:
📌 review: [vitamin C language] Chapter 4 - array (0x02 initialization of one-dimensional array)
1 point for each sub question, full score 7 points
💬 Predict the running result of the following code (sizeof)
int main()
{
char arr[] = {'a','b','c','d','e','f'}; // Character array
/* 1 */ printf("%d\n", sizeof(arr));
/* 2 */ printf("%d\n", sizeof(arr+0));
/* 3 */ printf("%d\n", sizeof(*arr));
/* 4 */ printf("%d\n", sizeof(arr[1]));
/* 5 */ printf("%d\n", sizeof(&arr));
/* 6 */ printf("%d\n", sizeof(&arr+1));
/* 7 */ printf("%d\n", sizeof(&arr[0]+1));
return 0;
}💡 answer:
/* 1 */ printf("%d\n", sizeof(arr)); // 6
/* 2 */ printf("%d\n", sizeof(arr+0)); // 4/8
/* 3 */ printf("%d\n", sizeof(*arr)); // 1
/* 4 */ printf("%d\n", sizeof(arr[1])); // 1
/* 5 */ printf("%d\n", sizeof(&arr)); // 4/8
/* 6 */ printf("%d\n", sizeof(&arr+1)); // 4/8
/* 7 */ printf("%d\n", sizeof(&arr[0]+1)); // 4/8 🔑 Resolution:
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Third question:
1 point for each sub question, full score 7 points
💬 Predict the running results of the following code (strlen)
int main()
{
char arr[] = { 'a','b','c','d','e','f' }; // Character array
/* 1 */ printf("%d\n", strlen(arr));
/* 2 */ printf("%d\n", strlen(arr + 0));
/* 3 */ printf("%d\n", strlen(*arr));
/* 4 */ printf("%d\n", strlen(arr[1]));
/* 5 */ printf("%d\n", strlen(&arr));
/* 6 */ printf("%d\n", strlen(&arr + 1));
/* 7 */ printf("%d\n", strlen(&arr[0] + 1));
return 0;
}
💡 answer:
/* 1 */ printf("%d\n", strlen(arr)); // Random value
/* 2 */ printf("%d\n", strlen(arr + 0)); // Random value
/* 3 */ printf("%d\n", strlen(*arr)); // error
/* 4 */ printf("%d\n", strlen(arr[1])); // error
/* 5 */ printf("%d\n", strlen(&arr)); // Random value
/* 6 */ printf("%d\n", strlen(&arr + 1)); // Random value - 6
/* 7 */ printf("%d\n", strlen(&arr[0] + 1)); // Random value - 1🔑 Resolution:
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Fourth question:
1 point for each sub question, full score 7 points
💬 Predict the running result of the following code (sizeof)
int main()
{
char arr[] = "abcdef";
/* 1 */ printf("%d\n", sizeof(arr));
/* 2 */ printf("%d\n", sizeof(arr+0));
/* 3 */ printf("%d\n", sizeof(*arr));
/* 4 */ printf("%d\n", sizeof(arr[1]));
/* 5 */ printf("%d\n", sizeof(&arr));
/* 6 */ printf("%d\n", sizeof(&arr+1));
/* 7 */ printf("%d\n", sizeof(&arr[0]+1));
return 0;
}
💡 answer:
/* 1 */ printf("%d\n", sizeof(arr)); // 7
/* 2 */ printf("%d\n", sizeof(arr+0)); // 4/8
/* 3 */ printf("%d\n", sizeof(*arr)); // 1
/* 4 */ printf("%d\n", sizeof(arr[1]));// 1
/* 5 */ printf("%d\n", sizeof(&arr)); // 4/8
/* 6 */ printf("%d\n", sizeof(&arr+1)); // 4/8
/* 7 */ printf("%d\n", sizeof(&arr[0]+1)); // 4/8🔑 Resolution:
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Fifth question:
1 point for each sub question, full score 7 points
💬 Predict the running results of the following code (strlen)
int main()
{
char arr[] = "abcdef";
/* 1 */ printf("%d\n", strlen(arr));
/* 2 */ printf("%d\n", strlen(arr + 0));
/* 3 */ printf("%d\n", strlen(*arr));
/* 4 */ printf("%d\n", strlen(arr[1]));
/* 5 */ printf("%d\n", strlen(&arr));
/* 6 */ printf("%d\n", strlen(&arr + 1));
/* 7 */ printf("%d\n", strlen(&arr[0] + 1));
return 0;
}💡 answer:
/* 1 */ printf("%d\n", strlen(arr)); // 6
/* 2 */ printf("%d\n", strlen(arr+0)); // 6
/* 3 */ printf("%d\n", strlen(*arr)); // error
/* 4 */ printf("%d\n", strlen(arr[1])); // error
/* 5 */ printf("%d\n", strlen(&arr)); // 6
/* 6 */ printf("%d\n", strlen(&arr+1)); // Random value
/* 7 */ printf("%d\n", strlen(&arr[0]+1)); // 5🔑 Resolution:
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Sixth question:
1 point for each sub question, full score 7 points
📌 review: [vitamin C language] Chapter 10 - Advanced pointer (Part 1) (definition of 0x00 character pointer)
💬 Predict the running result of the following code (sizeof)
int main()
{
char* p = "abcdef";
/* 1 */ printf("%d\n", sizeof(p));
/* 2 */ printf("%d\n", sizeof(p + 1));
/* 3 */ printf("%d\n", sizeof(*p));
/* 4 */ printf("%d\n", sizeof(p[0]));
/* 5 */ printf("%d\n", sizeof(&p));
/* 6 */ printf("%d\n", sizeof(&p + 1));
/* 7 */ printf("%d\n", sizeof(&p[0] + 1));
return 0;
}💡 answer:
/* 1 */ printf("%d\n", sizeof(p)); // 4/8
/* 2 */ printf("%d\n", sizeof(p+1)); // 4/8
/* 3 */ printf("%d\n", sizeof(*p)); // 1
/* 4 */ printf("%d\n", sizeof(p[0])); // 1
/* 5 */ printf("%d\n", sizeof(&p));// 4/8
/* 6 */ printf("%d\n", sizeof(&p+1)); // 4/8
/* 7 */ printf("%d\n", sizeof(&p[0]+1)); // 4/8🔑 Resolution:
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Question 7:
1 point for each sub question, full score 7 points
💬 Predict the running results of the following code (strlen)
int main()
{
char *p = "abcdef";
/* 1 */ printf("%d\n", strlen(p));
/* 2 */ printf("%d\n", strlen(p+1));
/* 3 */ printf("%d\n", strlen(*p));
/* 4 */ printf("%d\n", strlen(p[0]));
/* 5 */ printf("%d\n", strlen(&p));
/* 6 */ printf("%d\n", strlen(&p+1));
/* 7 */ printf("%d\n", strlen(&p[0]+1));
return 0;
}💡 answer:
/* 1 */ printf("%d\n", strlen(p)); // 6
/* 2 */ printf("%d\n", strlen(p+1)); // 5
/* 3 */ printf("%d\n", strlen(*p)); // error
/* 4 */ printf("%d\n", strlen(p[0])); // error
/* 5 */ printf("%d\n", strlen(&p)); // Random value
/* 6 */ printf("%d\n", strlen(&p+1)); // Random value
/* 7 */ printf("%d\n", strlen(&p[0]+1)); // 5🔑 Resolution:
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Question 8:
1 point for each sub question, with a full score of 11 points
💬 Predict the running result of the following code (sizeof)
int main()
{
int a[3][4] = {0}; // Two dimensional array
/* 1 */ printf("%d\n",sizeof(a));
/* 2 */ printf("%d\n",sizeof(a[0][0]));
/* 3 */ printf("%d\n",sizeof(a[0]));
/* 4 */ printf("%d\n",sizeof(a[0]+1));
/* 5 */ printf("%d\n",sizeof(*(a[0]+1)));
/* 6 */ printf("%d\n",sizeof(a+1));
/* 7 */ printf("%d\n",sizeof(*(a+1)));
/* 8 */ printf("%d\n",sizeof(&a[0]+1));
/* 9 */ printf("%d\n",sizeof(*(&a[0]+1)));
/* 10 */ printf("%d\n",sizeof(*a));
/* 11 */ printf("%d\n",sizeof(a[3]));
return 0;
}
💡 answer:
/* 1 */ printf("%d\n",sizeof(a)); // 48
/* 2 */ printf("%d\n",sizeof(a[0][0])); // 4
/* 3 */ printf("%d\n",sizeof(a[0])); // 16
/* 4 */ printf("%d\n",sizeof(a[0]+1)); // 4/8
/* 5 */ printf("%d\n",sizeof(*(a[0]+1)));// 4
/* 6 */ printf("%d\n",sizeof(a+1)); // 4
/* 7 */ printf("%d\n",sizeof(*(a+1))); // 16
/* 8 */ printf("%d\n",sizeof(&a[0]+1)); // 4/8
/* 9 */ printf("%d\n",sizeof(*(&a[0]+1))); // 16
/* 10 */ printf("%d\n",sizeof(*a)); // 16
/* 11 */ printf("%d\n",sizeof(a[3])); // 16🔑 Resolution:
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Summary:
📚 Meaning of array name:
① sizeof (array name) - the array name represents the entire array and calculates the size of the entire array.
② & array name, where the array name represents the whole array, and the address of the whole array is taken out.
③ In addition, all array names represent the address of the first element.
Gags:
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