Stage 6: C-Style String Handling (char[])

C-Style Strings: Char Arrays

Unlike the std::string class, C-style strings are simply arrays of elements of type char. The key element that distinguishes a regular character array from a "string" is the null terminator, written as \0. It tells functions like cout or printf where the text ends.

1. Declaration and Initialization

Remember that the array must always be 1 element larger than the number of characters you want to store to accommodate the \0.

cpp

char str[6] = "Hello"; // 5 characters + \0
char noSize[] = "Auto size"; // The compiler calculates the size automatically

2. Input and Output

According to your exam rules, you can use both iostream and cstdio.

Using iostream:

std::cin >> str; – Reads text up to the first whitespace. Risky as it may exceed the array size.
std::cin.getline(str, size); – The safest method. Reads a whole line (including spaces) and ensures the buffer is not overflowed.

Using cstdio:

scanf("%s", str); – Similar to cin, stops at whitespace.
printf("%s\n", str); – Fast way to print text.

3. Manual String Operations (Without <cstring>)

Since your list of allowed libraries does not include <cstring> (which contains strlen or strcpy), you must be able to perform these operations manually using loops. This is a common test of skill in exams.

Calculating Length (Custom strlen)

cpp

int getLength(char tab[]) {
    int i = 0;
    while (tab[i] != '\0') {
        i++;
    }
    return i;
}

Copying a String (Custom strcpy)

cpp

void copyString(char dest[], char source[]) {
    int i = 0;
    while (source[i] != '\0') {
        dest[i] = source[i];
        i++;
    }
    dest[i] = '\0'; // Very important: adding the null terminator at the end!
}

4. Pitfalls and Critical Errors

Missing \0: If you fill the array manually and forget the null terminator, cout will print characters until it happens to hit a zero in memory, resulting in "garbage" on the screen or a crash.
Buffer Overflow: Attempting to read 20 characters into a char[10] array. Always use cin.getline with the size specified.
Comparing Strings: if (str1 == str2) will not work correctly for char[] arrays (it compares memory addresses, not content). You must write your own function to compare them character by character.

Example: Comparing Strings

cpp

bool areEqual(char t1[], char t2[]) {
    int i = 0;
    while (t1[i] != '\0' && t2[i] != '\0') {
        if (t1[i] != t2[i]) return false;
        i++;
    }
    return t1[i] == t2[i]; // Check if both end at the same position
}

C-Style Strings: Char Arrays

1. Declaration and Initialization

Remember that the array must always be 1 element larger than the number of characters you want to store to accommodate the \0.

cpp

char str[6] = "Hello"; // 5 characters + \0
char noSize[] = "Auto size"; // The compiler calculates the size automatically

2. Input and Output

According to your exam rules, you can use both iostream and cstdio.

Using iostream:

std::cin >> str; – Reads text up to the first whitespace. Risky as it may exceed the array size.
std::cin.getline(str, size); – The safest method. Reads a whole line (including spaces) and ensures the buffer is not overflowed.

Using cstdio:

scanf("%s", str); – Similar to cin, stops at whitespace.
printf("%s\n", str); – Fast way to print text.

3. Manual String Operations (Without <cstring>)

Calculating Length (Custom strlen)

cpp

int getLength(char tab[]) {
    int i = 0;
    while (tab[i] != '\0') {
        i++;
    }
    return i;
}

Copying a String (Custom strcpy)

cpp

void copyString(char dest[], char source[]) {
    int i = 0;
    while (source[i] != '\0') {
        dest[i] = source[i];
        i++;
    }
    dest[i] = '\0'; // Very important: adding the null terminator at the end!
}

4. Pitfalls and Critical Errors

Missing \0: If you fill the array manually and forget the null terminator, cout will print characters until it happens to hit a zero in memory, resulting in "garbage" on the screen or a crash.
Buffer Overflow: Attempting to read 20 characters into a char[10] array. Always use cin.getline with the size specified.
Comparing Strings: if (str1 == str2) will not work correctly for char[] arrays (it compares memory addresses, not content). You must write your own function to compare them character by character.

Example: Comparing Strings

cpp

bool areEqual(char t1[], char t2[]) {
    int i = 0;
    while (t1[i] != '\0' && t2[i] != '\0') {
        if (t1[i] != t2[i]) return false;
        i++;
    }
    return t1[i] == t2[i]; // Check if both end at the same position
}

Stage 6: C-Style String Handling (char[])

C-Style Strings: Char Arrays

1. Declaration and Initialization

2. Input and Output

Using iostream:

Using cstdio:

3. Manual String Operations (Without <cstring>)

Calculating Length (Custom strlen)

Copying a String (Custom strcpy)

4. Pitfalls and Critical Errors

Example: Comparing Strings

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Stage 11: Pointer Arithmetic in C++

Stage 10: Pointers, Address-of, and Dereference Operators

Stage 4: Functions and Argument Passing in C++

Stage 6: C-Style String Handling (char[])

C-Style Strings: Char Arrays

1. Declaration and Initialization

2. Input and Output

Using iostream:

Using cstdio:

3. Manual String Operations (Without <cstring>)

Calculating Length (Custom strlen)

Copying a String (Custom strcpy)

4. Pitfalls and Critical Errors

Example: Comparing Strings

You might also like

Stage 11: Pointer Arithmetic in C++

Stage 10: Pointers, Address-of, and Dereference Operators

Stage 4: Functions and Argument Passing in C++