When we assign a string literal without specifying a size like:<\/strong><\/p>\nchar str[] = \"Hello\";<\/pre>\nC automatically calculates the size of the string literal “Hello”, including the null terminator \\0. So it allocates a char array of size 6 to store the string.<\/p>\n
The advantage of this method is that we don’t have to manually specify any size. C takes care of memory allocation based on the literal.<\/p>\n
The disadvantage is that we cannot resize the array later since the size is fixed at initialization.<\/p>\n
2) Assigning a String Literal With Size<\/h4>\n
When we specify a size like:<\/strong><\/p>\nchar str[50] = \"Hello\";<\/pre>\nHere, C will allocate a char array of size 50, initialize it with the literal “Hello”, and pad the remaining space with null terminators \\0.<\/p>\n
The advantage is that we can accommodate future string size increases up to the allocated memory.<\/p>\n
The disadvantage is that excess memory may get allocated if we specify a very large size.<\/p>\n
3) Character By Character Initialization With Size<\/h4>\n
When initializing character by character, we specify sizes like:<\/strong><\/p>\nchar str[6]; \r\nstr[0] = 'H';\r\nstr[1] = 'e'; \r\n...\r\nstr[5] = '\\0';<\/pre>\nHere, we have full control over each character inserted into the array. But it involves more work manually inserting each character.<\/p>\n
The size helps prevent accidental buffer overflows by limiting writes beyond the array size. But strings without null terminators can cause issues.<\/p>\n
4) Character By Character Initialization Without Size<\/h4>\n
We can also initialize strings character by character without specifying size:<\/strong><\/p>\nchar str[] = {'H','e','l','l','o','\\0'};<\/pre>\nC automatically allocates the size to hold the initialized characters plus the null terminator.<\/p>\n
This gives both flexibility of character by character initialization as well as safety of automatic memory allocation. But we lose the ability to resize arrays later.<\/p>\n
String Examples<\/h3>\n
Let’s look at some common programming examples related to strings in C:<\/strong><\/p>\n1. Printing Strings<\/h4>\n
We can print strings normally with printf:<\/strong><\/p>\nchar str[] = \"Hello World\";\r\nprintf(\"%s\", str);<\/pre>\nOutput:<\/strong>
\nHello World<\/p>\nTo print strings, use the%s format specifier.<\/p>\n
2. Reading String Input<\/h4>\n
To read a string from user input:<\/strong><\/p>\nchar str[50];\r\nscanf(\"%s\", str);\r\nprintf(\"%s\", str);<\/pre>\nInput:<\/strong>
\nDataFlair<\/p>\nOutput:<\/strong>
\nDataFlair<\/p>\n3. Reading Strings with Spaces<\/h4>\n
scanf() stops at whitespace. To read strings with spaces:<\/strong><\/p>\nchar str[50];\r\nfgets(str, 50, stdin);\r\nputs(str);<\/pre>\nInput:<\/strong>
\nDataFlair Tutorials<\/p>\nOutput:<\/strong>
\nDataFlair Tutorials<\/p>\nWe can also use scanf() with scanset:<\/strong><\/p>\nchar str[20];\r\nscanf(\"%[^\\n]s\", str);\r\nprintf(\"%s\", str);<\/pre>\n4. Finding String Length<\/h4>\n
Get string length with a loop:<\/strong><\/p>\nchar str[] = \"Hello\";\r\nint len = 0;\r\nwhile(str[len] != '\\0') {\r\n len++; \r\n}\r\nprintf(\"Length is: %d\", len);<\/pre>\nOutput:<\/strong>
\nLength is:<\/strong> 5<\/p>\nOr use strlen() from string.h<\/p>\n
5. Passing Strings to Functions<\/h4>\nvoid printStr(char str[]) {\r\n printf(\"%s\", str); \r\n}\r\nint main() {\r\n char str[] = \"DataFlair\";\r\n printStr(str);\r\n return 0;\r\n}<\/pre>\nOutput:<\/strong>
\nDataFlair<\/p>\nSo, in summary, strings in C can be used in various ways as illustrated by these examples. The key is choosing the right functions based on your specific string processing needs.<\/p>\n
String.h Functions<\/h3>\n
\n\n\n| Function<\/b><\/td>\n | Description<\/b><\/td>\n<\/tr>\n\n| strlen(s)<\/span><\/td>\n | Calculates the length of string s<\/span><\/td>\n<\/tr>\n\n| strcpy(s1, s2)<\/span><\/td>\n | Copies string s2 into string s1<\/span><\/td>\n<\/tr>\n\n| strcat(s1, s2)<\/span><\/td>\n | Concatenates string s2 to end of string s1<\/span><\/td>\n<\/tr>\n\n| strcmp(s1, s2)<\/span><\/td>\n | Compares string s1 and s2<\/span><\/td>\n<\/tr>\n\n| strchr(s,ch)<\/span><\/td>\n | Finds first occurrence of char ch in string s<\/span><\/td>\n<\/tr>\n\n| strstr(s1, s2)<\/span><\/td>\n | Finds first occurrence of string s2 in string s1<\/span><\/td>\n<\/tr>\n\n| strlwr(s)<\/span><\/td>\n | Converts string s to lowercase<\/span><\/td>\n<\/tr>\n\n| strupr(s)<\/span><\/td>\n | Converts string s to uppercase<\/span><\/td>\n<\/tr>\n\n| memcpy(s1, s2, n)<\/span><\/td>\n | Copies n chars from string s2 to s1<\/span><\/td>\n<\/tr>\n\n| memmove(s1, s2, n)<\/span><\/td>\n | Moves n chars from string s2 to s1<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n#include <stdio.h>\r\n#include <string.h>\r\n\r\nint main() {\r\n char s1[10] = \"hello\";\r\n char s2[10] = \"world\";\r\n \r\n \/\/ strlen()\r\n int len = strlen(s1);\r\n printf(\"Length of s1: %d\\n\", len);\r\n\r\n \/\/ strcpy() \r\n strcpy(s2, s1);\r\n printf(\"s2 after strcpy: %s\\n\", s2);\r\n\r\n \/\/ strcat()\r\n strcat(s1, s2);\r\n printf(\"s1 after strcat: %s\\n\", s1);\r\n\r\n \/\/ strcmp()\r\n int result = strcmp(s1, s2);\r\n if(result == 0) {\r\n printf(\"s1 and s2 are equal\\n\");\r\n } else {\r\n printf(\"s1 and s2 are not equal\\n\");\r\n }\r\n\r\n \/\/ strlwr()\r\n strlwr(s1);\r\n printf(\"s1 after strlwr: %s\\n\", s1);\r\n\r\n \/\/ strupr()\r\n strupr(s1);\r\n printf(\"s1 after strupr: %s\\n\", s1);\r\n return 0;\r\n}<\/pre>\nOutput:<\/strong><\/p>\nLength of s1:<\/strong> 5
\ns2 after strcpy:<\/strong> hello
\ns1 after strcat:<\/strong> hellohello
\ns1 and s2 are not equal
\ns1 after strlwr:<\/strong> hellohello
\ns1 after strupr:<\/strong> HELLOHELLO<\/p>\nInput and Output of Strings<\/h3>\nWe can use scanf() and printf() for input and output of strings in C:<\/strong><\/p>\n#include <stdio.h>\r\n\r\nint main() {\r\n char name[50];\r\n\r\n \/\/ Input string \r\n printf(\"Enter your name: \");\r\n scanf(\"%s\", name); \/\/ %s format specifier \r\n \r\n printf(\"Hello %s!\", name);\r\n \r\n return 0;\r\n}<\/pre>\nSome points to note:<\/strong><\/p>\n\n- %s format specifier is used in scanf() and printf() to read and write strings.<\/li>\n
- scanf() stops reading input at the first space, so it won’t read full strings containing spaces.<\/li>\n
- To read strings with spaces, you can use fgets().<\/li>\n<\/ul>\n
String Handling Best Practices<\/h3>\nWhen handling strings in C, some best practices include:<\/strong><\/p>\n | | | | | | | | | | |
![\"declaring](\"https:\/\/data-flair.training\/blogs\/wp-content\/uploads\/sites\/2\/2023\/09\/declaring-and-initializing-string-in-c.webp\")
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