Input Widgets

Text input, numeric input, and input validation in Dear ImGui

Input widgets allow users to enter and edit data. Dear ImGui provides input functions for text, integers, floats, and other data types.

Text Input

InputText()

Single-line text input:

IMGUI_API bool InputText(const char* label, char* buf, size_t buf_size, 
                         ImGuiInputTextFlags flags = 0, 
                         ImGuiInputTextCallback callback = NULL, 
                         void* user_data = NULL);

label · const char* · required

Widget label

buf · char* · required

Character buffer to edit

buf_size · size_t · required

Size of the buffer (including null terminator)

flags · ImGuiInputTextFlags · default: "0"

Optional input text flags (see below)

static char text[128] = "Hello, world!";
ImGui::InputText("##input", text, IM_COUNTOF(text));

if (ImGui::IsItemDeactivatedAfterEdit()) {
    // Text was edited and user pressed Enter or clicked away
    printf("Final text: %s\n", text);
}

InputTextMultiline()

Multi-line text input:

IMGUI_API bool InputTextMultiline(const char* label, char* buf, size_t buf_size,
                                  const ImVec2& size = ImVec2(0, 0),
                                  ImGuiInputTextFlags flags = 0,
                                  ImGuiInputTextCallback callback = NULL,
                                  void* user_data = NULL);

static char multiline[1024] = "Line 1\nLine 2\nLine 3";
ImGui::InputTextMultiline("##multiline", multiline, IM_COUNTOF(multiline),
                          ImVec2(-FLT_MIN, ImGui::GetTextLineHeight() * 16));

InputTextWithHint()

Text input with placeholder hint:

IMGUI_API bool InputTextWithHint(const char* label, const char* hint, 
                                 char* buf, size_t buf_size,
                                 ImGuiInputTextFlags flags = 0,
                                 ImGuiInputTextCallback callback = NULL,
                                 void* user_data = NULL);

static char email[128] = "";
ImGui::InputTextWithHint("##email", "Enter email address", email, IM_COUNTOF(email));

static char search[256] = "";
ImGui::InputTextWithHint("##search", "Search...", search, IM_COUNTOF(search));

Input Text Flags

Customize text input behavior with flags:

Character Filtering

// Numbers only
ImGui::InputText("##numbers", buf, 128, ImGuiInputTextFlags_CharsDecimal);

// Hexadecimal only
ImGui::InputText("##hex", buf, 128, ImGuiInputTextFlags_CharsHexadecimal);

// No blank characters
ImGui::InputText("##noblank", buf, 128, ImGuiInputTextFlags_CharsNoBlank);

// Uppercase only
ImGui::InputText("##upper", buf, 128, ImGuiInputTextFlags_CharsUppercase);

Common flags include:

• ImGuiInputTextFlags_EnterReturnsTrue - Return true when Enter pressed
• ImGuiInputTextFlags_Password - Display as password (***)
• ImGuiInputTextFlags_ReadOnly - Read-only mode
• ImGuiInputTextFlags_CharsDecimal - Allow 0-9 . + - *
• ImGuiInputTextFlags_CharsNoBlank - Filter out spaces and tabs

Numeric Input

InputInt()

Integer input with optional step buttons:

IMGUI_API bool InputInt(const char* label, int* v, int step = 1, int step_fast = 100,
                        ImGuiInputTextFlags flags = 0);

static int i0 = 123;
ImGui::InputInt("input int", &i0);

// With custom steps
static int i1 = 0;
ImGui::InputInt("input int (step)", &i1, 5, 20);

InputFloat()

Floating-point input:

IMGUI_API bool InputFloat(const char* label, float* v, 
                          float step = 0.0f, float step_fast = 0.0f,
                          const char* format = "%.3f",
                          ImGuiInputTextFlags flags = 0);

static float f0 = 0.001f;
ImGui::InputFloat("input float", &f0, 0.01f, 1.0f, "%.3f");

// Scientific notation
static float f1 = 1.e10f;
ImGui::InputFloat("input scientific", &f1, 0.0f, 0.0f, "%e");

InputDouble()

Double-precision input:

IMGUI_API bool InputDouble(const char* label, double* v,
                           double step = 0.0, double step_fast = 0.0,
                           const char* format = "%.6f",
                           ImGuiInputTextFlags flags = 0);

static double d0 = 999999.00000001;
ImGui::InputDouble("input double", &d0, 0.01, 1.0, "%.8f");

Multi-Component Input

InputFloat2/3/4()

Input multiple float values:

IMGUI_API bool InputFloat2(const char* label, float v[2], const char* format = "%.3f",
                           ImGuiInputTextFlags flags = 0);
IMGUI_API bool InputFloat3(const char* label, float v[3], const char* format = "%.3f",
                           ImGuiInputTextFlags flags = 0);
IMGUI_API bool InputFloat4(const char* label, float v[4], const char* format = "%.3f",
                           ImGuiInputTextFlags flags = 0);

static float vec2[2] = { 0.0f, 0.0f };
static float vec3[3] = { 0.0f, 0.0f, 0.0f };
static float vec4[4] = { 0.10f, 0.20f, 0.30f, 0.44f };

ImGui::InputFloat2("position", vec2);
ImGui::InputFloat3("direction", vec3);
ImGui::InputFloat4("color", vec4);

InputInt2/3/4()

Input multiple integer values:

IMGUI_API bool InputInt2(const char* label, int v[2], ImGuiInputTextFlags flags = 0);
IMGUI_API bool InputInt3(const char* label, int v[3], ImGuiInputTextFlags flags = 0);
IMGUI_API bool InputInt4(const char* label, int v[4], ImGuiInputTextFlags flags = 0);

static int ivec3[3] = { 10, 20, 30 };
ImGui::InputInt3("coordinates", ivec3);

Generic Scalar Input

InputScalar()

Input any scalar data type:

IMGUI_API bool InputScalar(const char* label, ImGuiDataType data_type, void* p_data,
                           const void* p_step = NULL, const void* p_step_fast = NULL,
                           const char* format = NULL, ImGuiInputTextFlags flags = 0);

data_type · ImGuiDataType · required

Data type:

• ImGuiDataType_S8, ImGuiDataType_U8
• ImGuiDataType_S16, ImGuiDataType_U16
• ImGuiDataType_S32, ImGuiDataType_U32
• ImGuiDataType_S64, ImGuiDataType_U64
• ImGuiDataType_Float, ImGuiDataType_Double

static ImS8 s8_v = 127;
static ImU8 u8_v = 255;
static ImS16 s16_v = 32767;

ImGui::InputScalar("int8", ImGuiDataType_S8, &s8_v);
ImGui::InputScalar("uint8", ImGuiDataType_U8, &u8_v);
ImGui::InputScalar("int16", ImGuiDataType_S16, &s16_v);

Input Validation and Callbacks

Use callbacks to validate or process input:

static int MyCallback(ImGuiInputTextCallbackData* data) {
    if (data->EventFlag == ImGuiInputTextFlags_CallbackCharFilter) {
        // Custom character filtering
        if (data->EventChar < 256 && strchr("0123456789ABCDEFabcdef", (char)data->EventChar)) {
            return 0;  // Accept
        }
        return 1;  // Reject
    }
    return 0;
}

static char hex_input[16] = "";
ImGui::InputText("Hex", hex_input, 16, 
                 ImGuiInputTextFlags_CallbackCharFilter, MyCallback);

Complete Example

void ShowInputDemo() {
    ImGui::Begin("Input Demo");
    
    // Text input
    static char text[128] = "Hello, world!";
    ImGui::InputText("Name", text, IM_COUNTOF(text));
    
    // Text with hint
    static char email[128] = "";
    ImGui::InputTextWithHint("Email", "[e-mail]", email, IM_COUNTOF(email));
    
    // Password
    static char password[128] = "";
    ImGui::InputText("Password", password, IM_COUNTOF(password), 
                     ImGuiInputTextFlags_Password);
    
    ImGui::Spacing();
    
    // Numeric inputs
    static int i0 = 123;
    ImGui::InputInt("Integer", &i0);
    
    static float f0 = 0.001f;
    ImGui::InputFloat("Float", &f0, 0.01f, 1.0f, "%.3f");
    
    static double d0 = 999.999;
    ImGui::InputDouble("Double", &d0, 0.01, 1.0, "%.3f");
    
    ImGui::Spacing();
    
    // Multi-component
    static float vec3[3] = { 0.0f, 3.14159f, 2.71828f };
    ImGui::InputFloat3("Vector", vec3);
    
    ImGui::Spacing();
    
    // Multiline text
    static char multiline[512] = "Line 1\nLine 2\nLine 3";
    ImGui::InputTextMultiline("##multiline", multiline, IM_COUNTOF(multiline),
                              ImVec2(-FLT_MIN, ImGui::GetTextLineHeight() * 8));
    
    ImGui::End();
}

Best Practices

Use ImGuiInputTextFlags_EnterReturnsTrue to detect when the user presses Enter to confirm input.

Always provide a buffer large enough for your expected input plus the null terminator.

Check IsItemDeactivatedAfterEdit() after an input widget to detect when editing is complete and the value has changed.