error about strcpy and strcmp

**kkkcj** · 12-17-2017

Code:

void modifyStaff() {
    char ans, cont, staid[20], name[25], position[20];
    int i = 0, pCount, modiCount = 0,salary,found;
    staff P[20];
    FILE*fp;
    fp = fopen("staff.dat", "rb");
    while (fread(&P[i], sizeof(staff), 1, fp))
        i++;
    pCount = i;
    fclose(fp);
    do {
        printf("\nEnter ID of the Staff to be modified : ");


        rewind(stdin);
        scanf("%s", staid);
        found = 0;


        printf("\nID    NAME   POSITION    SALARY \n");
        printf("============   ===========    ======= \n");
        for (i = 0; i < pCount; i++) {
            if (strcmp(staid, P[i].id) == 0) {
                found = 1;
                printf("%-18d %-10s %-10s %-10d \n",
                    P[i].id, P[i].name, P[i].salary, P[i].salary);
                printf("\n Updated Name:");
                scanf("%[^\n]", name);
                printf("\n Updated Position:");
                rewind(stdin);
                scanf("%[^\n]", position);
                printf("\n Updated salary:");
                rewind(stdin);
                scanf("%d", salary);
                printf("Confirm to Modify (Y=yes)? ");
                rewind(stdin);
                scanf("%c", &ans);
                if (toupper(ans) == 'Y') {
                    P[i].id = staid;
                    strcpy(P[i].name, name);
                    strcpy(P[i].position, position);
                    strcpy(P[i].salary, salary);
                    modiCount++;
                }
                printf("Updated Staff Records:\n");
                printf("\nID NAME POSITION SALARY\n");
                printf("========  ========= =========== ========\n");
                printf("%-18d %-10s %-10s %-10d", P[i].id, P[i].name, P[i].position, P[i].salary);
            }
        }
        if (!found)
            printf("NO record founded with ID =%d\n", staid);
        printf("Any more record to modify?(Y=yes)?");
        rewind(stdin);
        scanf("%c", &cont);
    } while (toupper(cont) == 'Y');
    fp = fopen("staff.dat", "wb");
    for (i = 0; i < pCount; i++)
        fwite(&P[i], sizeof(staff), 1, fp);
    fclose(fp);
    printf("\n\t%d Record(s) modified.\n\n", modiCount);
}

the compiler show bunch of error during the strcpy and strcmp function and i don't understand why

**GReaper** · 12-17-2017

Probably because the struct's name, position, salary and id aren't character arrays.

**kkkcj** · 12-17-2017

Code:

typedef struct staff {
	
	int id,salary;
	char name[30], position[30];


}staff;

**GReaper** · 12-17-2017

Ok then, as you see, id and salary aren't character arrays. Instead of strcmp and strcpy use == and = on them.

**kkkcj** · 12-17-2017

thank u very muchhh....there another question..it will only execute until the line 21...it wont execute the remain row

**GReaper** · 12-17-2017

Have you converted staid( which is a char array ) to an int? If you haven't, do so, and then compare the converted value with P[i].id

You can of course scrap "staid" completely and use an int, say "id", with scanf like this:

Code:

scanf("%d", &id);

Also, I said it before and I say it again: Stop using rewind with stdin.

**kkkcj** · 12-17-2017

Code:

void modifyStaff() {
	char ans, cont, name[25], position[20];
	int i = 0, pCount, modiCount = 0, found, id[20];
	int salary[20];
	staff P[20];
	FILE*fp;
	fp = fopen("staff.dat", "rb");
	while (fread(&P[i], sizeof(staff), 1, fp))
		i++;
	pCount = i;
	fclose(fp);
	do {
		printf("\nEnter ID of the Staff to be modified : ");


		scanf("%d",id);
		found = 0;


		printf("\nID    NAME   POSITION    SALARY \n");
		printf("============   ===========    ======= \n");
		for (i = 0; i < pCount; i++) {
			if (id==P[i].id == 0) {
				found = 1;
				printf("%-18d %-10s %-10s %-10d \n",
					P[i].id, P[i].name, P[i].position, P[i].salary);
				printf("\n Updated Name:");
				scanf("%[^\n]", name);
				printf("\n Updated Position:");
			
				scanf("%[^\n]", position);
				printf("\n Updated salary:");
				
				scanf("%d",salary);
				printf("Confirm to Modify (Y=yes)? ");
				
				scanf("%c", &ans);
				if (toupper(ans) == 'Y') {
					P[i].id =id;
					strcmp(P[i].name, name);
					strcmp(P[i].position, position);
					P[i].salary = salary;
					modiCount++;
				}
				printf("Updated Staff Records:\n");
				printf("\nID NAME POSITION SALARY\n");
				printf("========  ========= =========== ========\n");
				printf("%-18d %-10s %-10s %-10d", P[i].id, P[i].name, P[i].position, P[i].salary);
			}
		}
		if (!found)
			printf("NO record founded with this ID" );
		printf("Any more record to modify?(Y=yes)?");
		
		scanf("%c", &cont);
	} while (toupper(cont) == 'Y');
	fp = fopen("staff.dat", "wb");
	for (i = 0; i < pCount; i++)
		fwrite(&P[i], sizeof(staff), 1, fp);
	fclose(fp);
	printf("\n\t%d Record(s) modified.\n\n", modiCount);
}

it's work but when i modify the updated name and position will display together..and the cannot store the salary correctly....for example i modify the salary to become 9000 but it will show 12347487

**kkkcj** · 12-17-2017

and it will not change the original data..for example i modify the name kkk to become yyy, it still show the kkk instead of yyy

**Hodor** · 12-17-2017

Originally Posted by kkkcj

and it will not change the original data..for example i modify the name kkk to become yyy, it still show the kkk instead of yyy

You should be using strcpy and not strcmp to update the name and position (lines 40 and 41)

**kkkcj** · 12-17-2017

which mean i should use =?

**kkkcj** · 12-17-2017

i misunderstand it...i get it now...is the salary...

**kkkcj** · 12-17-2017

Code:

void modifyStaff() {
	char ans, cont, name[25], position[20];
	int i = 0, pCount, modiCount = 0, found, id[20];
	int salary[20];
	staff P[20];
	FILE*fp;
	fp = fopen("staff.dat", "rb");
	while (fread(&P[i], sizeof(staff), 1, fp))
		i++;
	pCount = i;
	fclose(fp);
	do {
		printf("\nEnter ID of the Staff to be modified : ");


		rewind(stdin);
		scanf("%d", id);
		found = 0;


		printf("\nID    NAME   POSITION    SALARY \n");
		printf("============   ===========    ======= \n");
		for (i = 0; i < pCount; i++) {
			if (id == P[i].id == 0) {
				found = 1;
				printf("%-18d %-10s %-10s %-10d \n",
					P[i].id, P[i].name, P[i].position, P[i].salary);
				printf("\n Updated Name:");
				rewind(stdin);
				scanf("%[^\n]", name);
				printf("\n Updated Position:");
				rewind(stdin);
				scanf("%[^\n]", position);
				printf("\n Updated salary:");
				rewind(stdin);
				scanf("%d", salary);
				printf("Confirm to Modify (Y=yes)? ");
				rewind(stdin);
				scanf("%c", &ans);
				if (toupper(ans) == 'Y') {
					P[i].id = id;
					strcpy(P[i].name, name);
					strcpy(P[i].position, position);
					strcpy(P[i].salary, salary);
					modiCount++;
				}
				printf("Updated Staff Records:\n");
				printf("\nID NAME POSITION SALARY\n");
				printf("========  ========= =========== ========\n");
				printf("%-18d %-10s %-10s %-10d", P[i].id, P[i].name, P[i].position, P[i].salary);
			}
		}
		if (!found)
			printf("NO record founded with this ID");
		printf("Any more record to modify?(Y=yes)?");
		rewind(stdin);
		scanf("%c", &cont);
	} while (toupper(cont) == 'Y');
	fp = fopen("staff.dat", "wb");
	for (i = 0; i < pCount; i++)
		fwrite(&P[i], sizeof(staff), 1, fp);
	fclose(fp);
	printf("\n\t%d Record(s) modified.\n\n", modiCount);
}

i change my code...but it does't work for the salary part...it display error access of violation

**Salem** · 12-17-2017

1. You forgot an &
2. Bizarrely, salary is an array of ints, not a single int.
3. All those rewind(stdin) are not doing anything for you.

> strcpy(P[i].salary, salary);
It only works with CHAR arrays.
Making salary an array of int doesn't make it something you can pass to strcpy.
Use P[i].salary = salary;
When you've fixed it to not be an array.

> if (id == P[i].id == 0)
What are you trying to do here?
You've written this
if (id == ( P[i].id == 0 ) )
The inner ( ) expression has a value of either 0 or 1.
So this if statement will only be true if id is 0 or 1.

**kkkcj** · 12-17-2017

Code:

typedefstruct staff {

int id, salary;
char name[30], position[30];
}staff;

void modifyStaff(){
char ans, cont, name[25], position[20];
int i =0, pCount, modiCount =0, found, id[20];
int salary[20];
staff P[20];
FILE*fp;
fp = fopen("staff.dat","rb");
while(fread(&P[i],sizeof(staff),1, fp))
    i++;
pCount = i;
fclose(fp);
do{
    printf("\nEnter ID of the Staff to be modified : ");

    rewind(stdin);
    scanf("%d",&id);
    found =0;

    printf("\nID    NAME   POSITION    SALARY \n");
    printf("============   ===========    ======= \n");
    for(i =0; i < pCount; i++){
        if(id == P[i].id ==0){
            found =1;
            printf("%-18d %-10s %-10s %-10d \n",
                P[i].id, P[i].name, P[i].position, P[i].salary);
            printf("\n Updated Name:");

            scanf("%[^\n]",&name);
            printf("\n Updated Position:");

            scanf("%[^\n]",&position);
            printf("\n Updated salary:");

            scanf("%d",&salary);
            printf("Confirm to Modify (Y=yes)? ");

            scanf("%c",&ans);
            if(toupper(ans)=='Y'){
                P[i].id = id;
                strcpy(P[i].name, name);
                strcpy(P[i].position, position);
                P[i].salary=salary;
                modiCount++;
            }
            printf("Updated Staff Records:\n");
            printf("\nID NAME POSITION SALARY\n");
            printf("========  ========= =========== ========\n");
            printf("%-18d %-10s %-10s %-10d", P[i].id, P[i].name, P[i].position, P[i].salary);
        }
    }
    if(!found)
        printf("NO record founded with this ID");
    printf("Any more record to modify?(Y=yes)?");

    scanf("%c",&cont);
}while(toupper(cont)=='Y');
fp = fopen("staff.dat","wb");
for(i =0; i < pCount; i++)
    fwrite(&P[i],sizeof(staff),1, fp);
fclose(fp);
printf("\n\t%d Record(s) modified.\n\n", modiCount);

i change the code as below...the salary cannot modify successfully ..for example i modify the salary form 600 become 700, the results will be 1767752

**kkkcj** · 12-17-2017

Code:

if(id == P[i].id ==0){
            found =1;

this is mean if the id user enter same as id store in system. print all the details and another question is the compiler will display the details even though the user user enter the wrong ID

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