C - 了解结构的值设置模式

Question

我已经构建了一个小的 C 程序，我正在尝试设置一个结构值

**static faut fautData**

typedef struct
{
    char ds[25];
    char ec[51];
    char vc[51];
    char rc[51];
    char rb[2];
    char eb[2];
    char vb[2];
    char es[10];
    char dias[50];
    char ss[10];
} faut;

我有一个函数名称更新来为上面指定的结构设置值

但是当我尝试设置 ** faut.es ** @更新函数的开头时，值没有被分配(在我的打印调用中它没有得到反射(reflect)。

当我在最后设置相同的值时，我能够打印输出并查看值

这是为什么呢？

示例代码

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

typedef struct
{
    char ds[25];
    char ec[51];
    char vc[51];
    char rc[51];
    char rb[2];
    char eb[2];
    char vb[2];
    char es[10];
    char dias[50];
    char ss[10];
} faut;


typedef struct
{
    unsigned int d5;
    unsigned int d10;
    unsigned int d20;
    unsigned int d50;
    unsigned int d100;
    unsigned int d500;
    unsigned int d1000;
    unsigned int an;
    unsigned int rn;
    unsigned int cn;
    int alr;

}ncd;

static ncd chkncd;
int cdc;

void admin_init(void)
{
    char Keys[17];
    int i = 0;
    int keysEnabled;
    int shift = 0x01;
    keysEnabled=0xFF;
    strcpy(Keys,"0000000000000000");
    //keysEnabled = getKeysToEnable();
    for(i=0;i<8;i++)
    {

        switch((keysEnabled & shift))
        {
            case 0x10:
                Keys[0]=0x34;
                Keys[1]=0x36;
                break;
            case 0x20:
                Keys[2]=0x34;
                Keys[3]=0x37;
                break;
            case 0x40:
                Keys[4]=0x34;
                Keys[5]=0x38;
                break;
            case 0x80:
                Keys[6]=0x34;
                Keys[7]=0x39;
                break;

            case 0x08:
                Keys[8]=0x34;
                Keys[9]=0x34;
                break;
            case 0x04:
                Keys[10]=0x34;
                Keys[11]=0x33;
                break;
            case 0x02:
                Keys[12]=0x34;
                Keys[13]=0x32;
                break;
            case 0x01:
                Keys[14]=0x34;
                Keys[15]=0x31;
                break;
            default:
                break;
        }
        shift = shift << 1;
    }
    printf("%s",Keys);

}

void update(void)
{
    char temp[512];
    int i = 0;
    static faut fautData;
    memset(&fautData, '\0', sizeof(fautData));
    int cat =0;
    if(cat) // Any failure
    {
        strncpy(fautData.ds, "3", 1);
        strncpy(fautData.es, "4", 1);
        memset(temp,'\0',sizeof(temp));
    }
    else
    {
        strncpy(fautData.es, "2",1);
        strncpy(fautData.ds, "0",2);
    }
    strcpy(&fautData.ec[0],"00000000000000000000000000000000000000000000000000");//00000000000000000000000000000000000000000000000000
    strcpy(&fautData.rc[0],"00000000000000000000000000000000000000000000000000");//00000000000000000000000000000000000000000000000000
    strcpy(fautData.vc,"");
    if(chkncd.d50 != 0){
        memset(temp,'\0',sizeof(temp));
        strcat(fautData.vc,"01");
        sprintf(temp, "%03d", chkncd.d50);
        strcat(fautData.vc,temp);
    }
    if(chkncd.d100 != 0){
        memset(temp,'\0',sizeof(temp));
        strcat(fautData.vc,"02");
        sprintf(temp, "%03d", chkncd.d100);
        strcat(fautData.vc,temp);
    }

    if(chkncd.d500 != 0){
        memset(temp,'\0',sizeof(temp));
        strcat(fautData.vc,"03");
        sprintf(temp, "%03d", chkncd.d500);
        strcat(fautData.vc,temp);
    }
    if(chkncd.d1000 != 0){
        memset(temp,'\0',sizeof(temp));
        strcat(fautData.vc,"04");
        sprintf(temp, "%03d", chkncd.d1000);
        strcat(fautData.vc,temp);
    }
    sprintf(fautData.vb, "%02d", chkncd.an);
    fautData.rb[0] = 0x30;
    fautData.rb[1] = 0x30;
    fautData.eb[0] = 0x30;
    fautData.eb[1] = 0x30;
    strncpy(fautData.dias, "0", 1);
    cdc = cdc - chkncd.an - chkncd.cn;
    if ((chkncd.alr) || (cdc < 2450))
        strncpy(fautData.ss, "4", 1);
    else
        strncpy(fautData.ss, "1", 1);
    sprintf(temp,"keysEnabled:\nds : %s\nec : %s\n vc : %s\nrc : %s\n rb : %s\n eb : %s\n vb : %s\n es : %s\n ss : %s\n",   fautData.ds,    fautData.ec,    fautData.vc,    fautData.rc,    fautData.rb,    fautData.eb,    fautData.vb,    fautData.es,    fautData.dias,  fautData.ss);
    printf("%s",temp);
}



int main(void) {

    cdc=2300;
    chkncd.d5=0;
    chkncd.d10=0;
    chkncd.d20=0;
    chkncd.d50=0;
    chkncd.d100=0;
    chkncd.d500=1;
    chkncd.d1000=0;
    chkncd.alr=0;
    chkncd.an=1;
    chkncd.rn=0;
    chkncd.cn=0;
    update();
    return EXIT_SUCCESS;
}

Answer 1

你的问题在这里:

sprintf(fautData.vb, "%02d", chkncd.an);

fautData.vb 是两个字节，但是您的 sprintf 调用将写入三个字节:两位数后跟一个空终止符，这会溢出 vb 数组并覆盖 fautData.es。