VS2019的调试功能学习（烫烫烫）
我编写了个大数减法的程序但是会出现很奇怪的报错，然后我就一路百度。。。
现在我们尝试对以下代码用VS2019进行调试修改bug：
//源文件main.cpp#include<stdio.h>#include<string.h>const int maxn = 1e3 + 10;/*int input(char a[],char b[]){int j=0;for(j=0;(a[j]=getchar())!='-';j++){if(a[j]!='0'&&a[j]!='1'&&a[j]!='2'&&a[j]!='3'&&a[j]!='4'&&a[j]!='5'&&a[j]!='6'&&a[j]!='7'&&a[j]!='8'&&a[j]!='9')return 0;}a[j]='\0';scanf('%s',b);return 1;}*/void sub(char a[], char b[], char c[], int la, int lb){//printf('%s\n%s\n',a,b);memset(c, '\0', sizeof(c));for (int i = 0; i < la / 2; i++) //进行翻转操作{char tmp = a[i];a[i] = a[la - 1 - i];a[la - 1 - i] = tmp;}for (int i = 0; i < lb / 2; i++){char tmp = b[i];b[i] = b[lb - 1 - i];b[lb - 1 - i] = tmp;}//printf('%s\n%s\n',a,b);for (int i = 0; i < la; i++) //减法操作{if (b[i] == '\0'){c[i] = a[i];//什么鬼continue;}c[i] = a[i] - b[i] + '0';if (c[i] < '0'){c[i] += 10;a[i + 1]--;}}int lc = strlen(c);for (int i = 0; i < lc / 2; i++){int tmp = c[i];c[i] = c[lc - 1 - i];c[lc - i - 1] = tmp;}//(c[0]=='0')?c[0]='\0':1;}int main(){char a[maxn], b[maxn], c[maxn];while (1/*input(a,b)*/){int j = 0;int la = 0, lb = 0;scanf('%s', a);scanf('%s', b);la = strlen(a);lb = strlen(b);sub(a, b, c, la, lb);printf('%s\n', c);memset(a, '\0', sizeof(a));memset(b, '\0', sizeof(b));memset(c, '\0', sizeof(c));}return 0;}
编译报错:严重性代码说明项目文件行 禁止显示状态错误 C4996 scanf
首先如果在VS2019中直接运行此代码会出现如下报错：
1>------ 已启动生成: 项目: Large number subtraction, 配置: Release Win32 ------1>main.cpp1>C:\Users\chenlon\source\repos\Large number subtraction\main.cpp(3,22): warning C4244: “初始化”: 从“double”转换到“int”，可能丢失数据1>C:\Users\chenlon\source\repos\Large number subtraction\main.cpp(67,1): error C4996: 'scanf': This function or variable may be unsafe. Consider using scanf_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS. See online help for details.1>D:\Windows Kits\10\Include\10.0.17763.0\ucrt\stdio.h(1274): message : 参见“scanf”的声明1>C:\Users\chenlon\source\repos\Large number subtraction\main.cpp(68,1): error C4996: 'scanf': This function or variable may be unsafe. Consider using scanf_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS. See online help for details.1>D:\Windows Kits\10\Include\10.0.17763.0\ucrt\stdio.h(1274): message : 参见“scanf”的声明1>已完成生成项目“Large number subtraction.vcxproj”的操作 - 失败。========== 生成: 成功 0 个，失败 1 个，最新 0 个，跳过 0 个 ==========
编译报错解决
之后终于在这个文章找到了解决办法：https://blog.csdn.net/weixin_42839965/article/details/81669145
1.右键单击工程名——>属性
2.将是改为否，单击确定
运用调试功能检查BUG
一、选择断点并检查程序
1.选择需要检查或暂停运行的行，如下图红色方框前
2.点击Windows调试器
3.对程序进行对应操作，检查运行结果
运行至此处时出现问题，注意观察该赋值运算前后字符串c的变化过程：
二、“烫烫烫”乱码：
出现以上问题的原因如下：
这种乱码最常见的地方是Visual Studio里。
Visual Studio中，未初始化的栈空间用0xCC填充，而未初始化的堆空间用0xCD填充。
而0xCCCC和0xCDCD在中文GB2312编码中分别对应“烫”字和“屯”字。
如果一个字符串没有结束符'\0'，输出时就会打印出未初始化的栈或堆空间的内容，这就是大名鼎鼎的“烫烫烫”乱码。
改了半天一直是这个问题，最终还是选择用int c[maxn]的数组来处理......
改完了
#include<stdio.h>#include<string.h>const int maxn = 1e3 + 10;int lc=0;int input(char a[],char b[]){int j=0;for(j=0;(a[j]=getchar())!='-';j++){if(a[j]!='0'&&a[j]!='1'&&a[j]!='2'&&a[j]!='3'&&a[j]!='4'&&a[j]!='5'&&a[j]!='6'&&a[j]!='7'&&a[j]!='8'&&a[j]!='9')return 0;}a[j]='\0';//将a[]中的'-'，去除scanf('%s',b);return 1;}void sub(char a[], char b[], int c[], int la, int lb){//printf('%s\n%s\n',a,b);for (int i = 0; i < la / 2; i++) //进行翻转操作{char tmp = a[i];a[i] = a[la - 1 - i];a[la - 1 - i] = tmp;}for (int i = 0; i < lb / 2; i++){char tmp = b[i];b[i] = b[lb - 1 - i];b[lb - 1 - i] = tmp;}//printf('%s\n%s\n',a,b);for (int i = 0; i < la; i++) //减法操作{if (b[i] == '\0'){c[i] = a[i] - 48;continue;}c[i] = a[i] - b[i];if (c[i] < 0){c[i] += 10;a[i + 1]--;}}lc = la;for (int i = la - 1; c[i] == 0; i--) //为了使结果开头不会有0{lc--;}for (int i = 0; i < lc / 2; i++){int tmp = c[i];c[i] = c[lc - 1 - i];c[lc - i - 1] = tmp;}}int main(){char a[maxn], b[maxn];int c[maxn];memset(a, '\0', sizeof(a));memset(b, '\0', sizeof(b));memset(c, 0, sizeof(c));while (input(a,b)){int j = 0, type = 0, la = 0, lb = 0;//scanf('%s', a);//scanf('%s', b);la = strlen(a);lb = strlen(b);if (la == lb){if (strcmp(a, b) > 0){type = 1;sub(a, b, c, la, lb);}else if(strcmp(a,b)<=0){sub(b, a, c, lb, la);type = -1;}else{printf('0\n');continue;}}else{if (la > lb){sub(a, b, c, la, lb);type = 1;}else{sub(b, a, c, lb, la);type = -1;}}if (type == -1) printf('-');for (int i = 0; i < lc; i++)printf('%d', c[i]);printf('\n');while (getchar() != '\n'); //getchar()是在输入缓冲区顺序读入一个字符(包括空格、回车和Tab)，为了去除之前的回车，在此处加此语句，牢记此使用技巧!memset(a, '\0', sizeof(a));memset(b, '\0', sizeof(b));memset(c, 0, sizeof(c));//好习惯}return 0;}
终于把这题过了！https://code.mi.com/problem/list/view?id=3
#include<stdio.h>#include<string.h>const int maxn = 1e3 + 10;int lc=0;int input(char a[],char b[]){int j=0;for(j=0;(a[j]=getchar())!='-';j++){if(a[j]!='0'&&a[j]!='1'&&a[j]!='2'&&a[j]!='3'&&a[j]!='4'&&a[j]!='5'&&a[j]!='6'&&a[j]!='7'&&a[j]!='8'&&a[j]!='9')return 0;}a[j]='\0';//将a[]中的'-'，去除scanf('%s',b);return 1;}void sub(char a[], char b[], int c[], int la, int lb){//printf('%s\n%s\n',a,b);for (int i = 0; i < la / 2; i++) //进行翻转操作{char tmp = a[i];a[i] = a[la - 1 - i];a[la - 1 - i] = tmp;}for (int i = 0; i < lb / 2; i++){char tmp = b[i];b[i] = b[lb - 1 - i];b[lb - 1 - i] = tmp;}//printf('%s\n%s\n',a,b);for (int i = 0; i < la; i++) //减法操作{if (b[i] == '\0'){c[i] = a[i] - 48;continue;}c[i] = a[i] - b[i];if (c[i] < 0){c[i] += 10;a[i + 1]--;}}lc = la;for (int i = la - 1; c[i] == 0; i--) //为了使结果开头不会有0{lc--;}for (int i = 0; i < lc / 2; i++){int tmp = c[i];c[i] = c[lc - 1 - i];c[lc - i - 1] = tmp;}}int main(){char a[maxn], b[maxn];int c[maxn];memset(a, '\0', sizeof(a));memset(b, '\0', sizeof(b));memset(c, 0, sizeof(c));input(a, b);int j = 0, type = 0, la = 0, lb = 0;//scanf('%s', a);//scanf('%s', b);la = strlen(a);lb = strlen(b);if (la == lb){if (strcmp(a, b) > 0){type = 1;sub(a, b, c, la, lb);}else if(strcmp(a,b)<=0){sub(b, a, c, lb, la);type = -1;}else{printf('0\n');}}else{if (la > lb){sub(a, b, c, la, lb);type = 1;}else{sub(b, a, c, lb, la);type = -1;}}if (type == -1) printf('-');for (int i = 0; i < lc; i++)printf('%d', c[i]);printf('\n');return 0;}
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